The Yale Law Journal


Customs, Immigration, and Rights: Constitutional Limits on Electronic Border Searches

01 Apr 2019

abstract. The warrantless search of travelers’ electronic devices as they enter and exit the United States is rapidly increasing. While the Supreme Court has long recognized a border-search exception to the Fourth Amendment’s warrant requirement, it applies to only two interests: promoting the duty regime and preventing contraband from entering the country; and ensuring that individuals are legally admitted. The government’s recent use of the exception goes substantially beyond these matters. U.S. Customs and Border Protection (CBP) and Immigration and Customs Enforcement (ICE) are using it to search electronic devices, and at times the cloud, for evidence of any criminal activity, bypassing the warrant requirement altogether. Searches of these devices implicate privacy concerns well beyond those of the home, which has long been protected even for customs and immigration purposes. This Essay traces the evolution of the border exception, noting the effect of recent Supreme Court decisions, to argue that CBP and ICE are operating outside constitutional constraints. The Essay considers two objections grounded in the legitimate interests of CBP and ICE. It responds, first, that inspection of digital devices differs from the examination of a traveler’s purse or luggage: the level of intrusion and the amount of information obtained changes the quality of the search, triggering Fourth Amendment protections. Second, as an immigration matter, as soon as citizens are identified, absent probable cause, the government does not have the constitutional authority to search their devices at all. Foreigners lacking a substantial connection to the country, however, do not enjoy the same Fourth Amendment protections. It concludes by observing that because of the substance and complexity of the issue, Congress has an important role to play in determining what types of searches are justified.


Over the past three years, the warrantless search of travelers’ electronic devices as they enter and exit the country has rapidly increased. In 2015, U.S. Customs and Border Protection (CBP) examined 8,503 devices. That number more than doubled the following year, before soaring in 2017 to more than 30,000 searches.1 In 2015, U.S. Immigration and Customs Enforcement (ICE), in turn, reported the search of 4,444 cell phone and 320 other electronic devices. In 2016, ICE eclipsed these numbers, searching 23,000 devices.2

The Supreme Court has long recognized a border-search exception to the Fourth Amendment’s warrant requirement. In United States v. Flores-Montano, the Court looked to the nation’s sovereign “interest in protecting . . . its territorial integrity” to justify such searches.3 In United States v. Montoya de Hernandez, the Court stated, somewhat more narrowly, that Congress is the source of the executive’s power. It explained that “[s]ince the founding of our Republic . . . [Congress has] granted the Executive plenary authority to conduct routine searches and seizures at the border, without probable cause or a warrant.”4 The Commerce Clause permits Congress to authorize the seizure of goods at the border.5

Congress and the courts endorsed only two justifications for broad border search authorities: first, “to regulate the collection of duties and to prevent the introduction of contraband into this country;”6 and, second, to ascertain which persons should be admitted to the United States.7For the latter, ensuring proper legal process (and immigration status) proved paramount.8 Looking to these areas, Congress empowered the executive to monitor “who and what may enter the country.”9 Congress did not provide an exception for ordinary law enforcement to use the movement of people to look for evidence of criminal activity. To the contrary, only customs agents and immigration officials could exercise authorities narrowly tailored to intercept contraband and control immigration.

Current electronic border searches eclipse the traditional limits placed on the executive to justify the departure from Fourth Amendment requirements. CBP and ICE search devices for any criminal activity, with no limits on use of the material in subsequent proceedings.10 The executive branch, moreover, has targeted individuals, using their movement across frontiers to obtain information that otherwise would require a warrant to access.11 Thus far, the courts have provided something of a backstop, chastising the executive in some of the more egregious cases.12 But in an increasingly globalized world in which citizens’ border crossings repeatedly expose them to intrusive government searches, the lack of Supreme Court attention and statutory law is of concern. It leaves rights at the mercy of each agency’s regulatory regime. As the Court recognized in Riley v. California, “the Founders did not fight a revolution to gain the right to government agency protocols.”13

The rights at stake are substantial. Electronic devices “implicate privacy concerns far beyond those implicated by the search of a cigarette pack, a wallet, or a purse.”14 Even the term “cell phone” is misleading, as “many of these devices are in fact minicomputers that also happen . . . to be used as a telephone.”15 Their distinguishing feature is the “immense storage capacity.”16 As the Court noted, “[m]ost people cannot lug around every piece of mail they have received for the past several months, every picture they have taken, or every book or article they have read.”17 With mobile devices, they can. The search of electronic devices differs from luggage searches in terms of volume as well as the type of information that can be obtained: medical records, location data, information regarding political beliefs or religious convictions, and details about intimate relationships—stretching back for decades. Further, electronic devices also provide a gateway to digital information stored in the cloud.18

A search of mobile devices compromises far more detailed and personal information than a search of an individual’s home, which traditionally has received the highest protections under the Fourth Amendment.19 For the latter, a warrant must describe with particularity what is being sought based on probable cause of involvement in specific crimes. Officers cannot simply cast about looking for any potential criminal activity. Search of an electronic device, though, allows law enforcement to scour countless areas of an individual’s life. It is the equivalent of looking not just at an individual’s home, but entering their bank, their car, and their workplace; accompanying them on dates and on social occasions; going to the PTA meeting with them, or to their local grocery store or mall; attending their places of worship; and sitting down next to them at the public library to make a record of everything they read.

Home warrants also are particularized in their execution against named individuals. In contrast, the search of an electronic device uncovers lots of data about extended family, friends, and acquaintances. Metadata pinpoints them at certain places at particular times. Otherwise password-protected social media accounts reveal what they know and believe, what they find amusing—or upsetting, and what their political views may be. Intimate thoughts, conveyed through email, remain even after users delete messages. Access to all of this stretches, potentially, years backwards in time.

As a substantive matter, what is present in a house or apartment is more limited than what can be obtained from the search of a mobile phone or computer. Inside the home, business records are far less likely to be found than at work. Financial data is bounded by time and records retention. Correspondence, at best, will be incomplete, and photographs generally will be only those that have been printed. In comparison, one phone may contain and provide access to all of an individual’s work documents (as well as some of their colleagues’), complete financial records, extensive correspondence, and every photo ever taken. From this, the number and quality of an individual’s intimate relationships can be discovered, and the strength of an individual’s social networks ascertained. Inside the home, there may only be traces of where an individual has gone outside the home (perhaps because of a souvenir here or there). On the phone, however, this information may be stored in map applications, address books, photograph and video metadata, and GPS records. A private library does not contain every book an individual has read. Electronic devices, in contrast, capture all digital print books, audio books, and internet-based materials an individual has read, as well as movies they have watched, jokes at which they’ve laughed, and statements made on social media with which they agree. This is far more information than law enforcement would be able to obtain by executing a physical warrant. By accessing a phone, moreover, if certain applications have been downloaded, law enforcement could gain access not just to the digital world, but also to the inside of the home itself.20

This Essay argues that the electronic searches CBP and ICE are conducting at ports of entry violate the Fourth Amendment. It documents the well-established, historical limitations on border searches that have served to justify the exception, and demonstrates how current practices fall well outside constitutional protections.21 It begins with the current CBP and ICE regulations that govern the search of travelers’ devices before laying out the history of customs border search authorities, observing that the primary purpose of these measures is and has always been to interdict contraband and to prevent uncustomed goods from entering the country. These limited aims, which relate to sovereignty, form the core justification behind the border search exception. Here, strong protections have been extended to the home, even where contraband may be at issue.

The Essay then turns to the evolution of immigration law, pointing out that the historical purpose of such measures has been (a) to establish identity, (b) to admit “desirable” aliens, and (c) to exclude others, subject to policies set by Congress. The only reason the border search exception applies at all is to permit Congress to achieve these objectives. Even then, the powers of search and seizure are subject to higher protections at the threshold of the home.

The Essay next focuses on Fourth Amendment doctrine, looking at how the circuit courts have come down on the question of electronic border searches before and after a string of recent Supreme Court cases challenging traditional doctrine: Riley,22 United States v. Jones,23 and Carpenter v. United States.24 Applying the two-part approach articulated by Chief Justice Roberts in Carpenter, which focused on the nature of the documents being sought and limitations on any legitimate expectations of privacy regarding the contents, this Part recognizes that the border search exception does not apply to electronic devices in the same way it does to the search of a traveler’s other belongings.25

The government considers its current practices constitutional in light of the status of electronic data as a form of “digital contraband”.26 The Essay responds with two arguments. First, just as bits and bytes constitute the functional equivalent of illegal material, so, too, does the search that is being undertaken represent the functional equivalent of the search of the home, and, potentially, every aspect of an individual’s life. For the same reasons that the Court in Riley rejected the search of electronic devices within U.S. borders, examination of the same at ports of entry constitutes precisely the type of search covered by the Fourth Amendment and, historically protected even in the context of customs and duties. Second, to the extent that one could argue that criminals could take advantage of such a rule to upload material to the cloud, cross the border, and then download it within the U.S. (thereby avoiding detection), in-person physical transit has never been a necessary to bring contraband into the United States. Where sent through the post, Fourth Amendment protections still apply. Additionally, in a digital world, it is not only as a traveler crosses the border that the government has an opportunity to intercept material. Electronic search provisions, recent changes to the Federal Rules of Criminal Procedure, and foreign intelligence authorities allow the government to identify illegal activities, conduct investigations, and access digital materials. At the border, a gradated search that distinguishes between reasonable suspicion for a basic (manual) search and probable cause for an advanced, forensic search would recognize that some level of suspicion is required at the outset to search devices, and that such searches ought not to be granted in toto, but should take place under narrowly-circumscribed limits absent the stronger showing of probable cause. Where such matters enter the domain of matters ordinarily encased in the home, the Fourth Amendment establishes more stringent protections.

The Essay also addresses the primary counterargument regarding immigration measures: that it is the role of immigration authorities to identify and to inquire into the type of person admitted to the United States. In response, it notes that U.S. persons, as soon as their identity as citizen or legal resident is established, are no longer subject to immigration search authorities. Thus, no search of U.S. persons’ electronic devices is justified under the immigration exception. For non-U.S. persons, who lack a substantial relationship to the United States, CPB and ICE have broader authority. One of the starkest examples of how the current regulations fail to provide adequate protections is in the realm of electronic communications, where, despite the use of passwords and encryption, travelers are denied the same privacies that would be extended to the same material if it were physically written on paper. The Essay concludes by reiterating the concern that current practices violate constitutional norms, acknowledging that once a traveler establishes their citizenship, their electronic devices can only be searched consistent with the Fourth Amendment probable cause and warrant requirements, and proposing a stronger role for Congress in developing a statutory regime for noncitizens seeking entry.

I. current regulatory regime

The rights at issue in the government’s search of electronic devices at the border are substantial. Even so, these searches are governed by agency regulations that do not account for the importance of the interests at stake. This Part briefly describes the existing regime.

CBP’s January 2018 guidelines allow for “basic” searches without suspicion.27 This means that the agency considers itself entitled to seize the mobile phones, tablets, and laptops of every U.S. citizen—including those of judges, Justices, and Members of Congress, and their colleagues, families and friends—without any suspicion of wrongdoing. With one exception, there are no statutory, regulatory, or, according to the agencies, constitutional limits on who can see this information, how long it can be kept, or how it can be used.28 For attorney-client-privileged material, or attorney work product, a “filter team” segregates protected material.29 There are no special protections provided for journalists, sensitive political material, trade secrets, medical information, or materials otherwise privileged at law. Information obtained from these searches can be shared with any federal, state, local, or foreign law enforcement agency.30 For “advanced” forensic searches, which involve connecting external equipment “to an electronic device not merely to gain access . . . but to review, copy, and/or analyze its contents,”31 customs officers must merely meet a standard of “reasonable suspicion of activity in violation of the laws enforced or administered by CBP, or in which there is a national security concern.”32

In December 2018, the Department of Justice Office of Inspector General released a report on CBP’s border searches, finding that the agency had violated its own guidelines by failing to limit its collection of electronic data and to delete information obtained.33 The problem was widespread: sixty-seven percent of the Electronic Media Reports examined contained inconsistencies.34 Officials had consistently failed, for instance, to disable data connections to networks prior to search of the devices; other information was simply copied onto thumb drives and kept.35 Although the 2018 Privacy Impact Assessment for CBP Border Searches of Electronic Devices stated that the Department of Homeland Security (DHS) should audit the agency’s collection of personally-identifiable information, nothing has yet been made publicly available.36

The equivalent 2009 ICE directive has not been updated since the last review in 2012.37 Like its CBP counterpart, the mandate applies to any item containing electronic or digital information.38 However, there are three critical differences which, as a formal matter, empower ICE to conduct even more intrusive searches. First, the document authorizes ICE Special Agents to “search, detain, seize, retain, and share electronic devices, or information contained therein, with or without individualized suspicion.”39 In the course of the search, the policy explicitly protects agents’ authority “to make written notes or reports or to document impressions relating to a border encounter in ICE’s paper or electronic recordkeeping systems.”40 Second, there is no heightened standard imposed for forensic searches. Instead, “[a]t any point during a border search, electronic devices, or copies of information therefrom, may be detained for further review either on-site at the place of detention or at an off-site location.”41 Searches can take place up to thirty days after the information is seized, with continuations subject to supervisory approval every fifteen days thereafter.42 Third, unlike CBP, which (ostensibly) only performs basic searches in the equivalent of “airplane mode,” ICE can access information held on the cloud.43

The disjunction between CBP and ICE to some extent reflects their respective streams of authority: customs and immigration. The former emphasizes finding contraband, while the latter focuses on the character of individuals entering the country—partially explaining ICE’s broader search powers in regard to online information and data stored on the cloud. Regardless, both agencies’ actions are merging into the realm of traditional law enforcement, raising troubling constitutional concerns.

II. customs border search authorities

Historically, the executive branch had latitude to conduct searches at the border without first establishing probable cause and obtaining a warrant. The breadth of that authority derived in part from the evolution of customs law. During the early colonial period, England understood customs searches as necessary in the context of commercial regulation, as customs provided an opportunity to ensure dominance in shipping and trade. Over time, the emphasis shifted to using customs to generate revenue. Officials thus obtained broad powers to search for, and to interdict, “uncustomed” materials. Following the American Revolution, the latter emphasis survived, laying the groundwork for today’s CBP authorities. This history matters: it demonstrates that the purpose of customs search authority is to generate revenue and to interdict contraband. Where such searches moved away from the border and entered onto private property, special protections applied. Both aspects—the purpose of the search and the restrictions applied in relation to the home—serve as a limit on the border search exception.

A. Colonial History: Commercial Regulation Versus Revenue Generation

England saw in the American colonies an opportunity to consolidate its dominance in global shipping and trade. Accordingly, the customs laws applied to the colonies initially focused on goods shipped to and from the Americas, requiring, first, that they be brought to England and, later, carried exclusively on English vessels.

As early as 1621, the Privy Council recognized the financial and commercial opportunities at stake, arguing that “the Commodities brought from” the colony of Virginia ought to be “appropriated unto his Majesties subjectes” instead of being “communicated to forraine countries.”44 The council accordingly adopted an ordinance requiring that “all Tobacco and other commodities” from Virginia shall “not be carried into any forraine partes until the same have beene first landed here and his Majesties Customes paid therefore.”45 In the first Navigation Act of 1651, Parliament went on to require that any materials to or from the Americas be carried on English ships.46 The goal was to prevent European powers from trading directly with the colonies.

Following the Stuart Restoration, in 1660 Parliament passed the second Navigation Act, re-entrenching the rule that colonial trade be carried out only on English vessels. The vessels had to be English-owned, operated by an English master, and carry a crew of which three-quarters must be English.47 The statute did not prevent foreign imports to the colonies—it merely required transport under the English flag. Three years later, Parliament tightened its grip with the third Navigation Act, requiring that any European commodities bound for the colonies first be taken to England, unloaded, and duties paid, prior to their return to North America.48 The goal was to establish a monopoly over colonial trade.

Over time, English statutes applied to the colonies shifted their focus from commercial regulation to revenue generation. The early navigation statutes erroneously assumed that most or all colonial trade involved overseas commerce.49 In the absence of regulation, intracolonial trade (not subject to duties) began to flourish, with commodities eventually making their way to Europe “to the great hurt and diminution of the Customs and of the trade.”50 Parliament closed this gap in the Navigation Act of 1673, requiring that a bond be paid on enumerated items where the ship travelled between plantations.51 The enforcement devices, though, were weak. They also differed from those in place in England: in the late seventeenth century, customs agents could search “any ship, house, or place soever” in London to search for prohibited goods.52 The Treasurer could provide a warrant to the customs commissions to examine trunks and boxes held at the Custom House in Southampton.53 There was no colonial equivalent.

Accordingly, in the eighteenth century, Britain assumed greater powers to search for, and to seize, colonial contraband.54 Lord Grenville, the First Lord of the Treasury, and Chancellor of the Exchequer, famously considered the colonies to be the best source of revenue, charging the colonies with a failure to offset the costs of their own defense.55 He repeatedly argued in Westminster for more stringent customs enforcement in North America. Many agreed, so when the Molasses Act expired, Parliament passed a measure that emphasized mercantilism and revenue generation. The preamble to the American Revenue Act of 1764, otherwise known as the Sugar Act, explained: “[I]t is expedient that new provisions and regulations should be established for improving the revenue of this kingdom, and for extending and securing the navigation and commerce between Great Britain and your Majesty’s dominions in America.”56 This statute, along with the Currency Act of 176457 (in which Britain assumed control of the colonial system of currency), laid the groundwork for the revolt that followed the introduction of the Stamp Act of 1765.58

B. Contraband in the Early American Republic

Following independence, when the United States found itself in need of revenue to pay for the war, customs inspectors continued to have broad search authorities. The fledgling country needed efficient customs enforcement mechanisms. Contraband meant a loss of revenues. Thus, from the earliest days of the Republic, customs inspectors could board vessels to search for contraband without first obtaining a warrant. To find the same items within a dwelling house, building, or other place, though, customs officers first had to obtain a warrant based upon “cause to suspect.”59

In 1789, the same year that Congress forwarded the Bill of Rights to the states for ratification, it enacted statutes setting duties, establishing international ports of entry, requiring vessels to report their contents, and providing for inspectors to board vessels to examine whether the stated goods comported with the items on board.60 Under the Act of July 31, 1789, officials could board any vessel “in which they shall have reason to suspect any goods, wares or merchandise subject to duty shall be concealed; and therein to search for, seize, and secure any such goods, wares or merchandise.”61 The statute drew a line at the threshold of the home: where agents suspected that such materials were concealed in a “dwelling house, store, building, or other place,” they could apply to a justice of the peace for a warrant to conduct a search for the goods, “and if any shall be found, to seize and secure the same for trial.”62 Congress passed additional statutes in 1790, 1793, and 1799, all of which underscored the importance of the enforcement of duties.63

Contemporaneous with the drafting and adoption of the Fourth Amendment, the First, Second, and Fourth Congresses signaled that there was no need to obtain a warrant for goods subject to forfeiture when held in a ship or vessel. The amendment did not include any exceptions in the text, but the “right of the people to be secure in their persons, houses, papers, and effects against unreasonable search and seizure” applied to domestic matters—not to goods crossing the border.64 Once such goods, however, were held in a warehouse, building, or dwelling within the United States, the law required that customs agents obtain a warrant before conducting a search.

Vehicles and goods in transit presented a particular conundrum, which Congress addressed in the Act of July 18, 1866.65 That statute made it lawful for any customs officer “to go on board of any vessel, as well without as within his district, and to inspect, search, and examine the same, and any person, trunk, or envelope on board, and to this end, to hail and stop such vessel if under way, and to use all necessary force to compel compliance.”66 The customs officer had the authority to seize the items where it appeared “that any breach or violation of the laws of the United States [had] been committed” whereby “such vessel, or the goods, wares, and merchandise, or any part thereof, on board of or imported by such vessel, is or are liable to forfeiture.”67 This provision paralleled the fleeing-felon exception: the government did not need to first approach a third party magistrate for a warrant. The logic was that a crime was underway. In the latter context, it was the commission of a felony, and in the former context, the failure to pay duties at the border. Pari passu, the statute empowered officers to “arrest any person engaged in such breach or violation” and to pursue and arrest anyone who tried to escape.68 Specifically, officers could stop, search, and examine “any vehicle, beast, or person on which or whom he . . . shall suspect there are goods, wares, or merchandise which are subject to duty or shall have been introduced into the United States in any matter contrary to law.”69 The statute reflected the importance of securing things to prevent the illegal movement of uncustomed goods—namely, the vehicle, animals, “goods, wares, or merchandise, and all other appurtenances, including trunks, envelopes, covers, and all means of concealment, and all the equipage, trappings, or other appurtenances of such beast.”70

C. Contemporary Border Search Authorities

In 1930, the Smoot-Hawley Tariff Act increased tariffs on agricultural and industrial goods.71 Eight years later, an amendment to the act provided for special inspection, examination, and search authorities.72 As subsequently amended, the law empowers customs officers, acting pursuant to regulations issued by the Secretary of the Treasury or the Customs Service, to “enforce, cause inspection, examination, and search to be made of the persons, baggage, and merchandise discharged or unladen from” vessels arriving at U.S. ports, regardless of whether the goods have previously undergone inspection.73

In carrying out their duties, customs officers may board any vessel or vehicle “without as well as within [their] district[s],” in order to “examine the manifest and other documents and papers” and “examine, inspect, and search the vessel or vehicle and every part thereof and any person, trunk, package, or cargo on board.”74 Customs officers “may hail and stop such vessel or vehicle, and use all necessary force to compel compliance.”75 The Treasury Secretary has the authority to issue regulations for searching persons and baggage.76 Further, “all persons coming into the United States from foreign countries shall be liable to detention and search by authorized officers or agents of the Government under such regulations.”77

As a matter of case law, the level of suspicion required to search travelers for illegal goods as they cross the border increases as the search becomes more intrusive. Courts, for instance, do not require particularized suspicion for the contents of a traveler’s briefcase, luggage, purse, or pockets.78 Nor is it required for documents within containers inside such items.79 Pictures, films, and other graphic materials do not earn any higher level of protection.80 Minimal suspicion is sufficient to warrant a pat-down.81 In comparison, the search of a travelers’ undergarments and strip searches require “real suspicion.”82 The only context thus far recognized by the Supreme Court as requiring individualized suspicion is related to the intimate physical search of a woman believed to be smuggling drugs in her alimentary canal.83 In the 1985 case United States v. Montoya de Hernandez, customs officials suspected that a woman had swallowed balloons containing drugs.84 The Supreme Court determined that reasonable suspicion was required to detain the individual until the drugs had passed.85 This decision followed a series of lower court cases rejecting mere suspicion for intrusive body searches, requiring a “clear indication” or “plain suggestion” of criminal activity.86

Vehicle searches are subject to a less rigorous standard than are searches of persons. In United States v. Flores-Montano, reasonable suspicion was not considered necessary for removing a gas tank to search for contraband.87 The Supreme Court, however, has held open the possibility “that some searches of property are so destructive as to require” particularized suspicion.88

D. Mail Search

The discussion above addresses goods and materials crossing U.S. borders. Special laws address the search of items sent through the postal system, where stronger protections are afforded to citizens’ communications. These measures sharply contrast with the lack of restrictions over CBP’s current search of electronic mail—the modern-day equivalent of the post.

In regard to traditional communications, customs officers do not have the authority to open and inspect mail weighing sixteen ounces or less.89 They may only read correspondence contained in mail sealed against inspection once they have obtained either (a) written consent by the sender or addressee or (b) a search warrant from a judicial officer that meets the requirements of Rule 41 of the Federal Rules of Criminal Procedure.90 These restrictions do not apply to mail that has not been sealed against inspection.91 The key difference is the sealing of the document.

Mail weighing more than sixteen ounces that has been sealed against inspection can only be opened and searched by a customs officer where there are reasonable grounds to suspect that it contains (a) monetary instruments, (b) a weapon of mass destruction, or (c) material related to one of six categories.92 These include: exportation or importation of monetary instruments;93 material related to obscenity or child pornography;94 controlled substances;95 nuclear materials covered by the Export Administration Act;96 defense articles and services;97 and emergency matters that fall within the International Emergency Economic Powers Act, such as foreign exchange, transfers of credit or payments, or the import or export of currency or securities.98

A different provision in the code, the origins of which stem from nineteenth-century statutes, deals specifically with opening trunks or envelopes on board vessels.99 The standard set is “reasonable cause.” The statute authorizes customs offers boarding vessels to “search any trunk or envelope, wherever found, in which he may have a reasonable cause to suspect there is merchandise which was imported contrary to law.100 The Court has upheld the reasonable-suspicion test as applied to border searches as constitutional.101

E. Extended Border Search and the Functional Equivalent

For searches away from ports of entry, courts look at whether such actions can be upheld as “extended border searches” (i.e., searches proximate to the border) as well as whether they take place at the “functional equivalent” of the border (i.e., a place that may be far from the physical border, but which acts as border crossing).102 Airports, for instance, are considered the functional equivalent of the border.103 The validity of such searches depends upon a variety of factors, suggesting a totality-of-circumstances test. As with searches at the actual border, the Fourth Amendment standard of “reasonableness” still applies; however, mere suspicion is sufficient.104

In cases of continuous surveillance of vehicles transiting the border, courts have upheld searches twenty miles from the border that occur fifteen hours after entry.105 On the other hand, for roving searches, the Supreme Court has held invalid a warrantless search, twenty-five miles north of the border, on an east-west highway located at all points at least twenty miles from border, absent probable cause and reasonable suspicion.106 There is no border exception outside the actual border or its functional equivalent.107

F. Special Protections Afforded to the Home

As the Supreme Court noted in 1977, “a port of entry is not a traveler’s home.”108 For centuries, the courts have applied special protections to the latter. From the time of Coke’s Institutes (and, arguably, the Magna Carta), except in instances of a fleeing felon or the hue and cry, common law forbade access to the home absent a particularized warrant.109 The need for such a document increased pressure on what, precisely, would satisfy the requirement.

In the seventeenth and eighteenth centuries, the Crown began to make use of general warrants: documents issued by the monarch or a judicial officer, which were not based on any prior evidence of wrongdoing. Instead, general warrants were used to find criminal activity. They lacked particularity regarding the person or place to be searched, or the papers or records to be seized. They were not supported by oath or affirmation. The risk was that such nonparticularized warrants could be used to target individuals opposed to the Crown, and to find some reason (or excuse) to subject them to legal process. Treatise writers and jurists roundly condemned the practice as unreasonable—in other words, against the reason of the common law.110 Only specific warrants, issued by a magistrate, naming the individual, establishing probable cause for a specific crime, and supported by oath or affirmation, met the standard.111 The Framers incorporated this common law rule into the Fourth Amendment.112

Even with a warrant, there were strict limits on what could be sought. Particularized warrants only permitted officers to search for the fruits and instrumentalities of a crime. They could not look for “mere evidence.” This rule did not fall out of favor until 1967, just a few months prior to the Supreme Court’s decision in Katz v. United States.113

As a matter of customs law, from the beginning, Congress and the courts drew a distinction between a store or dwelling house, or other structure for which a proper warrant was required, and the search of a ship, motorboat, wagon, or automobile, where it was not practicable to obtain a warrant because the vehicle could be quickly moved. Thus, under the Act of March 3, 1815, it was not only lawful to board and search vessels within the customs officers’ districts and those adjoining, but also to stop and search any vehicle, beast, or person for whom there was probable cause to believe unlawful goods had been brought into the United States.114 The Court considered it a valid exercise of constitutional power.115 To the extent that a question of distance from the border arose, in the nineteenth century, the Attorney General drew the line at three miles.116

In this way, the border exception also bore a striking resemblance to the fleeing felon exception: it was only in the hot pursuit of goods illegally brought into the country that broader powers could be exercised. Limits still applied. “It would be intolerable and unreasonable,” the Court explained, “if a prohibition agent were authorized to stop every automobile on the chance of finding liquor, and thus subject all persons lawfully using the highways to the inconvenience and indignity of such a search.”117 As the Court wrote in Carroll v. United States:

Travelers may be so stopped in crossing an international boundary because of national self-protection reasonably requiring one entering the country to identify himself as entitled to come in, and his belongings as effects which may be lawfully brought in. But those lawfully within the country, entitled to use the public highways, have a right to free passage without interruption or search unless there is known to a competent official, authorized to search, probable cause for believing that their vehicles are carrying contraband or illegal merchandise.118

In Carroll, the Court noted the necessity of establishing probable cause of a felony for a search that occurred away from the border. The border was only relevant insofar as it helped to establish probable cause.119

Reflecting these traditions, customs searches of homes currently require a warrant, issued by a third-party federal judge or magistrate, and supported by probable cause that merchandise has been illegally brought into the United States, or that the goods in question are subject to forfeiture.120 The search of vehicles or vessels, however, is not limited to the time and place of actual international crossings.121

G. Restrictions on Customs Searches: Who and Why

Even when the customs exception applies, not every government official is permitted to exercise the associated enforcement powers. Courts have held that an “officer of the customs” includes customs officers, inspectors, investigators, and mail entry aides, certain Immigration and Naturalization Service officials (such as border patrol agents), and Coast Guard officers.122 The term also includes a doctor aiding a customs search.123 The right to undertake border searches does not extend to the FBI or to law enforcement when acting for general law enforcement purposes.

In the 1979 case of United States v. Vidal Soto-Soto, for example, the Ninth Circuit considered the FBI’s warrantless search of a Chevrolet pickup truck at the border to determine whether it had been stolen.124 The agent’s sole basis for stopping the truck was the make and model of the vehicle.125 Instead of evaluating the case under the customs search exception, the court instead looked to the Supreme Court’s recent decision in Delaware v. Prouse, in which it had required articulable and reasonable suspicion that a motorist was unlicensed or an automobile not registered to detain a vehicle and request the registration papers.126

The broader search authority granted to customs officers is based on the need to interdict things illegally brought into the country. As the Ninth Circuit noted, “[v]alidity for this distinction is found in the fact that the primordial purpose of a search by customs officers is not to apprehend persons, but to seize contraband property unlawfully imported or brought into the United States.”127 The court observed that “[t]he authorization of section 581 [19 U.S.C. § 1581] is to ascertain whether there are any dutiable articles concealed in the vessel; it is not to discover acts of criminality.”128 The purpose is “to effectuate the provisions of the navigation and tariff laws and to protect the revenue of the United States.”129 It is not to deter criminal activity writ large.130

III. immigration border search authorities

Immigration law has followed a different trajectory from provisions related to uncustomed goods and contraband. The doctrine is fraught with contradictions regarding the constitutional power of federal versus state entities.131 At the same time, history demonstrates that the primary aim of federal immigration inspection has been (a) to establish travelers’ identity; (b) to ensure that travelers meet the requirements for legal entry; and (c) to collect money to fund immigration services. An additional immigration interest—namely, keeping convicted criminals out of the country—only applies to non-citizens. This aim sheds light on some of the differences between CBP and ICE regulations.

In 1790, pursuant to Article I, Section 8 of the Constitution, Congress introduced rules for naturalization; however, it did not institute any restrictions on immigration.132 Through the late nineteenth century, immigration to the United States was thus relatively unregulated.133 In 1875, Congress passed the first federal immigration law.134 That statute entrusted the inspection of immigrants to customs collectors at the ports of entry. It excluded criminals and prostitutes and prohibited human trafficking of individuals from Asia.135 The inspectors had to ensure that these statutory requirements were met, which could only be done at the point of arrival. That same year, the Supreme Court ruled that immigration was a matter reserved to the federal government.136

In Chy Lung v. Freeman, the Court considered a California law that had extended significant powers of inspection, the ability to charge for every examination, and the ability to set a bond for each passenger, to the state Commissioner of Immigration.137 Justice Miller, writing for the Court, observed: “The passage of laws which concern the admission of citizens and subjects of foreign nations to our shores belongs to Congress, and not to the States.”138 Congress’s dominion over international commerce and its ability to shape U.S. foreign affairs were tied to its ability to regulate immigration.139

Fifteen years later, in Chae Chan Ping v. United States, the Court stated that although the Constitution did not explicitly address immigration, Congress had the general power to pass a statute amending prior treaties and excluding Chinese citizens.140 Justice Field, writing for the Court, said, “[t]he question whether our government is justified in disregarding its engagements with another nation is not one for the determination of the courts.”141 The decision fell to the political branches, rendering any judicial “reflection upon [Congress’s] motives, or the motives of any of its members,” immaterial.142 The Court wrote:

That the government of the United States, through the action of the legislative department, can exclude aliens from its territory is a proposition which we do not think open to controversy. Jurisdiction over its own territory to that extent is an incident of every independent nation. It is a part of its independence. If it could not exclude aliens it would be to that extent subject to the control of another power.143

Such authority was part of the foreign affairs power of any country, found in the interstices of Article I, Section 8, and Article II.144

With the authority to pass immigration laws firmly in federal hands, Congress passed a series of statutes providing for powers of inspection. Some laws, particularly those related to Chinese exclusion and contract labor, focused on establishing the identity of travelers.145 Under the Chinese Exclusion Act of 1882, for instance, the collector of customs in the district from which Chinese laborers departed from the United States were empowered to “go on board each vessel” and “make a list” of all Chinese laborers, entering the information into registry books with details on each worker’s “name, age, occupation, last place of residence, physical marks or peculiarities, and all facts necessary for . . . identification.”146 The same year, Congress passed another law that established a system of central control and created new classes of aliens that would be inadmissible to the United States based on whether they were likely to become a public burden or exhibited dubious moral character.147 Measures also addressed revenue generation, which gave inspectors further powers at the ports of entry.148

In 1891, Congress passed its first comprehensive immigration law, creating a Bureau of Immigration within the Treasury Department to administer all immigration laws (except the Chinese Exclusion Act), and further restricted immigration by adding inadmissible classes of persons, empowering the Secretary of Treasury to issue rules for inspection along the Canadian border, and directing the deportation of illegal aliens.149 In 1893, Congress augmented the reporting requirements to include travelers’ occupation, marital status, literacy, money in possession, and physical as well as mental health.150 A decade later, Congress expanded the list to provide for the exclusion of aliens based on political views—including “anarchists, or persons who believe in, or advocate, the overthrow by force or violence the government of the United States, or of all government, or of all forms of law, or the assassination of public officials.”151 In 1907, Congress expanded exclusion to cover “imbeciles”, “feeble-minded persons”, persons with physical or mental defects, persons afflicted with tuberculosis, children unaccompanied by their parents, persons who admitted the commission of a crime involving moral turpitude, and women entering the country for immoral purposes.152 Just as certain classes of people were excluded, others were encouraged to enter, including artists, singers, ministers, professors, and domestic servants. Immigration officials had the power to make inquiries necessary for these determinations.

In 1907, Congress established a Joint Commission on Immigration to consider the entire system and ten years later implemented the Commission’s recommendations.153 The 1917 statute added new excludable classes and a literacy test, and created the Asiatic Barred Zone, which encompassed much of the Asian continent.154 During World War I, Congress further passed a measure to give the President broad power to control the entry and exit of aliens in the interests of public safety.155

For the balance of the twentieth century, immigration measures focused on defining admissible aliens.156 These statutes, without exception, focused on establishing identity, encouraging individuals from certain countries (or with experience in skilled industries or strong connections to the United States) to immigrate, while prohibiting other classes of aliens considered undesirable or a threat to the country. A few measures expanded the classes of deportable offenses, such as those directed at aliens convicted of crimes related to weapons, bombs, or illegal drugs, those who had perpetrated fraud to gain entry, and illegal immigrants.157

By the beginning of the twenty-first century, the role of immigration inspectors had expanded to include: inspecting and admitting individuals arriving at ports of entry; administering benefits (such as naturalization); granting asylum; patrolling the borders; and apprehending and removing aliens who enter illegally, violate requirements of their admission, or present a threat.158 The emphasis throughout this time, and continuing to the present day, was on ascertaining the identity and citizenship of U.S. citizens and aliens seeking entry to the United States.

As the Supreme Court has recognized, citizens and individuals with a substantial connection to the United States benefit from the protections of the Fourth Amendment in their interactions with immigration officials.159 Non-U.S. persons lacking these characteristics, however, have no such rights. Immigration officials thus have broader authorities as to aliens: they can be interrogated, arrested, and subjected to more intrusive searches, including searches, “without warrant, of the person and of [their] personal effects,” where the immigration officer has “reasonable cause to suspect that grounds exist for denial of admission to the United States.”160 Congress, to date, has not made any special exceptions for the personal effects that may be searched. As a result, guidance on electronic devices has been left to the agencies themselves.

Despite the broader leeway provided to search of aliens, as with customs measures, the law still recognizes the greater privacy protections afforded to the home, as well as the application of the Fourth Amendment within U.S. borders. Thus, even though immigration authorities have the power to search for aliens domestically, the law requires either consent or a properly-executed warrant to enter onto farm land or any agricultural operation to interrogate individuals as to their right to be in the United States.161

IV. applicable fourth amendment doctrine

As CBP and ICE have made increasing use of their border search authorities, calls to exempt electronic devices from the exception to the warrant requirement have increased.162 The argument is that these devices contain a tremendous amount of private information not accessible in a routine border search. Prior to the Supreme Court’s decisions in Riley v. California, United States v. Jones, and Carpenter v. United States, courts generally rejected the argument based on the grounds that the search was routine and did not require reasonable suspicion (pursuant to the border search exception), or that the actual search in question had been conducted with reasonable suspicion.163 However, a few courts did determine that forensic examination required a higher standard.164 Since Riley and Carpenter, more courts have questioned—and rejected—unfettered access to citizens’ electronic devices.165 These courts are correct. The Fourth Amendment places a limit on the search of electronic devices, at least as to U.S. persons and individuals who have a substantial connection to the United States.

A. Cases Before Riley and Carpenter

Although the Supreme Court in Flores-Montano left open the possibility, under certain circumstances, that reasonable suspicion could be required for certain property searches at the border,166 several courts, prior to Riley and Carpenter, considered the search of electronic devices to fall within the ordinary border search exception. Others determined that in the particular case before them, reasonable suspicion had been met. Still others extended special protections to forensic searches.

1. Cases Holding Electronic Border Searches Are Not Subject to Reasonable Suspicion

Several of the cases permitting electronic border searches without reasonable suspicion derive from incidents involving child pornography. In United States v. Arnold, for instance, a traveler named Michael Arnold arrived at Los Angeles International Airport after a nearly twenty-hour flight from the Philippines.167 When Arnold went to clear customs, CBP pulled him aside for secondary questioning, inspected his luggage, and found a laptop, a separate hard drive, a USB stick, and six disks. Agents directed him to turn on his computer. On the desktop, agents found folders labeled “Kodak Pictures” and “Kodak Memories.” When agents opened the folders, they found photos of naked women. CBP called in ICE, who, believing the pictures to include children, detained and questioned the traveler. They seized his computer and the storage devices and, two weeks later, obtained a warrant. The Department of Justice charged Arnold with transporting child pornography.

Despite the amount of information that could be held on the computer, the court did not see that the search raised any Fourth Amendment concerns. Neither of the narrow grounds laid out by the Supreme Court in Flores-Montano that would require reasonable suspicion (“exceptional damage to property” or “particularly offensive manner”) applied.168 The court was “satisfied that reasonable suspicion is not needed for customs officials to search a laptop or other personal electronic storage devices at the border.”169 When a similar case arose in regard to fraudulent alien cards, which were found on a traveler’s hard drive while crossing the border, the Ninth Circuit considered the requirement of reasonable suspicion to be foreclosed by Arnold.170

The Fourth Circuit reached a similar conclusion in United States v. Ickes.171 In that case, the defendant, driving a van that appeared to be packed with everything he owned, crossed the U.S.-Canada border. A search of the van uncovered a video camera with a tape of a tennis match in which the camera was focused on a young ball boy. Border agents found marijuana seeds and pipes and several photo albums of child pornography. They also found a computer and seventy-five diskettes with additional child pornography on them. The court ruled the search permissible on the grounds that “[b]oth Congress and the Supreme Court have made clear that extensive searches at the border are permitted, even if the same search elsewhere would not be.”172 At least one other published lower court opinion reached a similar conclusion.173

2. Cases Finding that the Search Was Supported by Reasonable Suspicion

Unlike Arnold and the cases where the judiciary has dispensed with the reasonable suspicion requirement, in other instances, courts ruled that reasonable suspicion of criminal activity was present at the time of the electronic search. The first set of cases stemmed from ongoing criminal investigations related to the traveler that agents became aware of during the border encounter; the second derived from agents observing suspicious activity or uncovering illegal substances during the individual’s transit.

In United States v. Hassanshahi, a traveler's laptop was seized during an international border stop at a U.S. airport.174 An inquiry into the travelers identity revealed he was the subject of an ongoing federal investigation into a conspiracy to build a computer production facility in Iran in violation of U.S. trade embargoes. The court in that case considered agents to have established reasonable suspicion sufficient to support a forensic examination of the laptop.175 Similarly, in United States v. Saboonchi, a traveler’s name came up in connection with two different export violation investigations.176 The government had information that the defendant had purchased two cyclone separators that had then been shipped overseas to an entity linked to a company in Iran. The court determined that the forensic search of the defendant’s smart phone and flash drive had been supported by reasonable suspicion.177 Meanwhile, in United States v. Cotterman, the Ninth Circuit determined that border agents had reasonable suspicion for their initial search because the defendant had a prior conviction for child molestation, frequently traveled to a country associated with sex tourism, and carried password-protected files.178 A handful of lower courts found the presence of illegal substances during the search to be sufficient for the examination of electronic devices.179

3. Cases Extending Special Protections to Forensic Investigations

A third category of cases prior to Riley and Carpenter extended Fourth Amendment protections to more intrusive forensic investigations. The most prominent case came out of the Ninth Circuit. In United States v. Cotterman, agents entered a traveler’s name into the Treasury Enforcement Communication System (TECS), which revealed a 15-year old child sexual molestation charge. Agents referred the defendant and his wife for secondary questioning, ordering them to leave their car and belongings behind. A search of the vehicle yielded two laptop computers with password-protected files. The defendant offered to assist agents in accessing the information, but the agents declined because of concern that the defendant would use the opportunity to sabotage the files. Agents seized the computers and transported them to Tucson, 150 miles away, for forensic evaluation. Over the course of three days, agents found seventy-five images of child pornography.180

The court determined that border searches must be limited in time and distance: agents needed to have reasonable suspicion that the subject was involved in criminal activity. Further, mere suspicion was not enough to justify a search.181 The court recognized the unique nature of the type of information contained in electronic devices:

The amount of private information carried by international travelers was traditionally circumscribed by the size of the traveler’s luggage or automobile. This is no longer the case. Electronic devices are capable of storing warehouses full of information . . . . Laptop computers, iPads and the like are simultaneously offices and personal diaries. They contain the most intimate details of our lives: financial records, confidential business documents, medical records and private emails . . . . Electronic devices often retain sensitive and confidential information far beyond the perceived point of erasure, notably in the form of browsing histories and records of deleted files. This quality makes it impractical, if not impossible, for individuals to make meaningful decisions regarding what digital content to expose to the scrutiny that accompanies international travel.182

A second case, this time in the District of Maryland, held that the forensic border search of any computer or electronic device should be considered nonroutine and therefore require reasonable suspicion.183 The court’s justification was that, while the government has legitimate concerns about child pornography, those concerns do not justify an unregulated assault on citizens’ private information—which is what is involved in forensic examination of a hard drive.184

In United States v. Saboonchi, the court took a different approach than that followed in Cotterman, where the court had determined that the forensic search of a computer that had been imaged was as invasive of the defendant’s privacy as a strip search.185 The Saboonchi court took issue with the Ninth Circuit’s failure to provide guidelines for what constituted a “forensic” search. Distinguishing between routine and nonroutine border searches, the court tried to construct a test for determining when a conventional computer search becomes a forensic investigation:

A conventional search at the border of a computer or device may include a Customs officer booting it up and operating it to review its contents, and seemingly, also would allow (but is not necessarily limited to) reviewing a computer’s directory tree or using its search functions to seek out and view the contents of specific files or file types . . . . And, just as a luggage lock does not render the contents of a suitcase immune from search, a password protected file is not unsearchable on that basis alone.186

In contrast, the Saboonchi court said, a forensic search involves the creation of a bitstream copy that is then “searched by an expert using highly specialized analytical software—often over the course of several days, weeks or months—to locate specific files, [] recover hidden, deleted, or encrypted data, and analyze the structure of files” and the drive.187 The court provided three explanations for why forensic searches should be considered sui generis: first, such a search creates a copy and uses specialized software to analyze the computer’s contents, creating the potential for an unbounded search; second, it provides access to deleted material; and third, it provides insight into an individual’s actions away from the border that would not otherwise be discoverable.188

In a similar vein, the First Circuit, in evaluating other kinds of searches, has offered the following nonexhaustive list of factors that may be relevant when determining whether a search can be characterized as routine:

(i) whether the search results in the exposure of intimate body parts or requires the suspect to disrobe; (ii) whether physical contact between Customs officials and the suspect occurs during the search; (iii) whether force is used to effect the search; (iv) whether the type of search exposes the suspect to pain or danger; (v) the overall manner in which the search is conducted; and (vi) whether the suspect’s reasonable expectations of privacy, if any, are abrogated by the search.189

These factors appear to be directed towards ascertaining the degree of intrusiveness of the search and its affect on the traveler—elements central to Fourth Amendment concerns.

B. Riley v. California: Stronger Constitutional Protections for Mobile Devices

The above cases predated Riley v. California, in which the Supreme Court recognized the unique incursions into privacy occasioned by the search of a mobile device.190 In holding that search of a cell phone incident to arrest required a warrant supported by probable cause, the Court underscored the distinction between electronic devices and other, physical items. The sheer capacity of mobile devices had important implications for privacy.191

In Riley, the court noted that more than ninety percent of American adults own and carry cell phones, keeping “on their person a digital record of nearly every aspect of their lives—from the mundane to the intimate.”192 The type of information gleaned differs in important respects from what can be uncovered from physical search. Cell phones contain medical records, location information, relationship details, political beliefs, religious convictions—in fact, more than could be ascertained even from the search of an individual’s home.193 Beyond this, mobile phones provide a gateway to vast amounts of data stored remotely in the cloud. The Court in Riley was unsatisfied with the government’s proposal to “disconnect a phone from the network before searching the device,”194 which CBP has adopted for electronic border searches. For the Court, even disconnected from the cloud, mobile phones contained vast amounts of private data.

One of the first border search cases to apply Riley was United States v. Kim, in which the court determined that the question of electronic searches was settled neither by the border exception nor by application of what was meant by “forensic.”195 Instead, the court in Kim considered the extent to which the search “intrudes upon an individual’s privacy on the one hand, and, on the other, the degree to which it is needed for the promotion of legitimate governmental interests.”196 The court noted:

[W]hile the courts in Ickes, Cotterman, and Saboonchi had little in the way of Supreme Court precedent to guide their way, the Supreme Court has since issued its opinion in Riley v. California. And in Riley, the Court made it clear that the breadth and volume of data stored on computers and other smart devices make today’s technology different in ways that have serious implications for the Fourth Amendment analysis.197

Under a totality of circumstances test, the court found that the imaging and search of a laptop, for an unlimited period and without any limits on the scope of the analysis, invaded the traveler’s privacy to such an extent that it was unreasonable under the Fourth Amendment.198The court noted that “given the vast storage capacity of even the most basic laptops, and the capacity of computers to retain metadata and even deleted material, one cannot treat an electronic storage device like a handbag simply because you can put things in it and then carry it onto a plane.”199

The Kim case is notable not just for its application of Riley, but because it involved a decision by investigators to wait until a suspect left the United States before using the border exception to search his laptop and thereby obtain detailed information about his activities.200 The court ultimately rejected the agents’ approach of using the border search exception to obtain information to which they otherwise would not be entitled.201

Despite Kim, the government has argued that the courts have “repeatedly rejected” applying Riley to the border search exception.202 That statement is misleading: while a number of Ninth Circuit lower court cases have not applied Riley, they are bound by Cotterman unless the court finds the two cases to be “clearly irreconcilable.”203 Similarly, lower courts in the Fourth Circuit are subject to Ickes.204

Other courts post-Riley have considered forensic examination of mobile phones to be nonroutine and have allowed searches only upon a showing of individualized suspicion or probable cause. In United States v. Kolsuz, the Fourth Circuit held that the forensic border search of a mobile device required individualized suspicion.205 In that case, Mr. Kolsuz was detained when CBP uncovered firearms parts in his luggage.206 Agents seized his phone and subjected it to a month-long forensic examination, generating a nearly 900-page report on the contents of the device. The district court determined that, under Riley, the forensic investigation was nonroutine but justified by reasonable suspicion.207 The Fourth Circuit agreed that nonroutine searches require some level of individualized suspicion. It did not, however, reach the question of whether reasonable suspicion was sufficient, or if probable cause was required.208 Because probable cause had been present, the good faith exception applied and the court was not required to suppress the information.

In United States v. Molina-Isidoro, the Fifth Circuit declined to announce a rule regarding the application of the border search exception to the modern technologies for which the Supreme Court, in Riley, had recognized increased privacy interests.209 Its rationale is of note: having found several kilos of methamphetamine in the traveler’s suitcase, CBP looked at some applications on her phone. According to the court, “the nonforensic search of Molina-Isidoro’s cell phone at the border was supported by probable cause. That means, at a minimum, the agents had a good-faith basis for believing the search did not run afoul of the Fourth Amendment.”210

In United States v. Vergara, a divided Eleventh Circuit panel considered the warrantless forensic search of three phones at the border.211 The majority stated: “Border searches ‘never’ require probable cause or a warrant. And we require reasonable suspicion at the border only ‘for highly intrusive searches of a person’s body such as a strip search or an x-ray examination.’”212 Judge Jill Pryor, dissenting, agreed “that the government’s interest in protecting the nation is at its peak at the border,” but she faulted the majority for ignoring the implications of Riley.213 In her view, “a forensic search of a cell phone at the border requires a warrant supported by probable cause.”214

C. The Effect of Carpenter v. United States

As with Riley, the Court’s decision in Carpenter v. United States has implications for how to think about electronic border searches.215 In that case, a man arrested for a series of robberies provided the mobile telephone numbers of his alleged accomplices to the FBI.216 Prosecutors applied for a court order under the Stored Communications Act to direct service providers to supply them with “[a]ll subscriber information, toll records and call detail records including listed and unlisted numbers dialed or otherwise transmitted to and from [the] target telephones” as well as “cell site information for the target telephones . . . for incoming and outgoing calls” for the suspects.217

Concerned by the volume and intrusiveness of location information, the Court created an exception to third-party doctrine.218 Its reasoning built on the so-called “shadow majority” in United States v. Jones, in which five justices adopted the view that individuals have a reasonable expectation of privacy in the whole of their physical movements.219 For the Court, the purpose of the Fourth Amendment was to secure the privacies of life from arbitrary power and to place obstacles in the way of excessive government surveillance.220 Over the years, technology had repeatedly disrupted that balance. Justice Roberts, citing Justice Brandeis’s dissent in Olmstead v. United States, explained that as “more far-reaching means of invading privacy . . . become available to the Government,” it was up to the Court “to ensure that the ‘progress of science’ does not erode Fourth Amendment protections.”221 Just as Kyllo v. United States responded to sense-enhancing technology (in that case, thermal imaging),222 Riley had recognized the “vast store of sensitive information” available on a mobile device.223 In jettisoning the application of the third-party doctrine to geolocational data, the Court focused on two areas: the nature of the documents being sought and limitations on any legitimate expectations of privacy. Both factors should shape border search doctrine going forward.224

1. Nature of Documents Being Sought

In examining the nature of the documents sought, Chief Justice Roberts first looked at the number of people implicated, observing that there are approximately 400 million electronic devices in the United States, making virtually everyone in America subject to the provisions.225 The Court acknowledged that the type of information at stake conveyed the intimate details of one’s life. It was “detailed, encyclopedic, and effortlessly compiled,”226—not unlike the massive amount of information contained on a mobile phone, iPad, or computer. It provided near perfect recall, making the data different than information that could be conveyed by another individual—even a party to the underlying action in question.227 The fact that the information was broad and increasingly more nuanced mattered, as did the fact that the resource constraints on obtaining such information were falling away.228 The Court noted its concern that the information was retroactive, giving “police access to a category of information otherwise unknowable.”229 Based on these observations, the Court determined that the data at issue was particularly sensitive and therefore deserved protections not afforded by third-party doctrine.

Each of the factors highlighted by the Court applies to the search of mobile devices at the border. Most people entering or leaving the country carry their electronic devices with them to satisfy a host of logistical and recreational needs. Travelers also need their devices once they reach their destination. This information provides deep insight into the most intimate aspects of travelers’ lives.

It is possible, of course, for users to delete all of the information from their devices, to place it on a hard drive or on the cloud, and to later restore it; or, alternatively, to use a different telephone or laptop devoid of any private information. But in addition to contradicting the basic Fourth Amendment position articulated by the Court in Carpenter, it would be an unreasonable expectation and one with numerous harmful consequences. For instance, it may be expensive to purchase a hard drive or cloud access, or to rent (or buy) an alternative device. At the very least, it would take time and may well exceed the average traveler’s technological knowledge. For individuals who use their travel time to work, to answer email, or to prepare for meetings, deleting this information would be highly disruptive and result in a detrimental impact on productivity. For those using the devices for personal or social reasons, they would be unable to do so while en route. Such an approach would essentially create a technological black hole at the border, while opening up the possibility that all travelers’ data could be intercepted when they restore information overseas. Alternatively, while overseas, citizens might lose access to possibly vitally-important data, unless they could access the cloud. One possible counterargument is that travelers could simply place their devices in airplane mode. But this does nothing to eliminate access to everything held on the device itself, which the Court in Riley was at pains to note included the full range of the privacies of life.

The Court in Carpenter, moreover, acknowledged the privacy interests at stake in geolocational data in particular. Most mobile devices contain GPS chips, which allow them to communicate with satellites to pinpoint a user’s location. Location data can then be logged by the device and various applications. Google Maps, for example, logs your information as you move and stores where you have been. That history is accessible to anyone who accesses the device. Social media platforms like Foursquare, Twitter, or Facebook include location information when you post.230 Location data, unless expressly turned off, is further embedded in photographs and videos as geotags—i.e., the precise longitude and latitude of where the photo was taken—and time stamps. Under Carpenter, search of this information is a search for Fourth Amendment purposes, and it requires a warrant, supported by probable cause, to access it for seven days or more.231

The same characteristics of geolocational data, additionally, apply to the myriad types of information held on an electronic device. They incorporate calendars, address books, private correspondence, financial records, memos, and documents of every sort, as well as pictures, books travelers have read or are reading, and detailed information on intimate relationships. Like cell site location information (CSLI), such information is “detailed, encyclopedic, and effortlessly compiled.”232 For the Court in Carpenter, the level of detail and precision and retroactive nature of the data all mattered. By using the map function or the GPS chip, the government can not only “travel back in time to retrace a person’s whereabouts,”233 but can also access all of the user’s correspondence—for decades, possibly—even when the user has tried to delete this information from their laptop. In searching electronic devices, the government can access data not just for information held on the actual machine, but for data stored in the cloud. The upshot is that the government, without any probable cause, can subject an individual’s entire life to scrutiny, bypassing the Fourth Amendment altogether. As for the diminishing resource constraints, this is no less true of border searches: where before the government would have had to obtain a warrant, send officers, and knock and announce at a home before entering to search, now, at the push of a button, all of the information that could have otherwise been obtained from the home—plus a great deal more—can be collected from electronic devices at the border.

2. Legitimate Expectations of Privacy

The second aspect of the Court’s inquiry regarding the expectation of privacy with respect to geolocational data is no less relevant to border search of electronic devices writ large. The Court noted that location data was not in any sense voluntarily shared. Mobile phones have become such a pervasive part of life that they are not optional.234 The Court further acknowledged that individuals do not have to do anything to have their location recorded by the service provider, nor is it an option not to create a record.235 Therefore, in no meaningful sense is there an assumption of risk.236

In obtaining information during a border search directly from the phone itself, and not from the service provider, the third-party doctrine drops away altogether. As for the argument that a traveler assumes the risk that border agents will search their electronic devices, only one of two options might apply.

First, the argument could be made that, by using an electronic device, an individual summarily consents to, or assumes the risk that, the government will search it. But this is plainly not true.237 Individuals do not knowingly and voluntarily share their lives with the government simply by using digital devices. Mobile phones, tablets, and computers are private, often encrypted, and protected by multiple passwords for different applications. The devices are stored inside the home, often replacing many of the records that would otherwise be documented on paper and placed in filing cabinets and drawers. And consumers demand that providers exercise network security. As ours has become a digital world, these documents have evolved, but their essential quality remains. Simply by living in the modern world, individuals do not assume a new risk that the government will gain access to their most sensitive information. Such logic flies in the face of the Court’s holding in Riley.

The second possibility would be that by moving or traveling with an electronic device across the border, individuals assume the risk that their entire lives will be examined by the government. But it is contradictory to say that mobile electronic devices have become an integral part of life, such that it is necessary to have them to live in the modern world, and then to say that such devices are optional when one travels abroad. They are not. This argument also does not comport with the Fourth Amendment’s prohibition on general warrants, as was recognized in the Supreme Court’s holding in Verdugo-Urquidez.238 U.S. citizens do not forfeit their Fourth Amendment rights when they travel overseas. The government’s argument would create a Constitution-free zone at every port of entry, where citizens have Fourth Amendment rights inside and outside the United States, but not as they cross the border. That is not how the Constitution works. It applies to the people of the United States at all times. Just as the fact that the geolocational records in Carpenter were obtained from a third party was not enough to overcome Fourth Amendment interests,239 so too is the fact that an electronic search occurs at the border insufficient to overcome citizens’ constitutional rights.

D. Digital Communications and Electronic Mail

As was detailed earlier in this Essay, special protections extend to the transfer of physical mail across the border. These further illustrate the extent to which CBP and ICE practices in regard to digital communications run afoul of constitutional limits—a limit explicitly recognized by the Court in Carpenter as a modern analogue.240

As aforementioned, officials inspecting mail that weighs less than sixteen ounces must first obtain a warrant to ensure that Fourth Amendment standards are met. This rule provides a sharp contrast to CBP’s current practice regarding email. To be sure, warrants are not required for paper correspondence unless the mail is sealed. But the equivalent in the digital realm is use of a password or encryption. At present, though, CBP policy permits agents to read travelers’ emails with no suspicion of any wrongdoing whatsoever, and, under the current regulations, CBP and ICE can insist that travelers provide the passwords to their electronic devices. Barring cooperation, they can simply keep the machines and use sophisticated techniques to bypass the protections otherwise instituted to keep prying eyes from seeing personal information.

The distinction between the protections afforded digital and paper correspondence does not track the relevant privacy interests, which apply equally to many forms of digital communications: from emails and text messages, to communications embedded in applications such as Instagram or WhatsApp Messenger. Regardless of the medium, they memorialize the substance of communications between individuals that would be protected under the Fourth Amendment if it were written on paper. While the sealing of the envelope plays a key role in the doctrine for paper correspondence, there is no relevant difference in a traveler’s decision to password-protect electronic devices as well as access to email, text messages, or applications.

While the Fourth Amendment requires only reasonable suspicion to access to mail that weighs more than sixteen ounces or for trunks or envelopes on board vessels transiting the border,241 that standard is still higher than that currently required for border searches of electronic devices. For the latter, no suspicion whatsoever is required. In addition, postal provisions that allow the government to search mail weighing over sixteen ounces or trunks or envelopes on board vessels, only allow officials to look for money, weapons of mass destruction, or contraband falling into one of the six categories. Even then, the government may only search for contraband based on reasonable suspicion of uncustomed goods. No provision permits monitoring for criminal or political activity writ large. Yet such searches are entirely consistent with the current regime governing electronic search at the border, regardless of the volume or extent of the files being inspected.

V. digital contraband, customs, and immigration

Customs and immigration both deal with the movement of physical objects. As this Essay has explained, the purpose behind these regimes is not to identify general criminal activity.242 It is to prevent contraband and uncustomed goods from crossing the border, and to ascertain the identity and citizenship of individuals seeking entry to determine whether to admit foreign nationals.243 Before concluding, it is important to narrow the discussion to recognize two potential challenges grounded in the legitimate interests of CBP and ICE.

A. Illegal Goods

How should we think about illicit materials that happen to be digitized? A strong argument could be mounted that digital contraband, after all, is still contraband and thus well within CBP’s domain. This is a sort of reverse of the functional rule of equivalence that I have elsewhere argued should govern the Court’s Fourth Amendment jurisprudence.244 Applied in this context, the argument runs: digital contraband still functions as material that Congress has prohibited, often because of the risk of harm. Just because something is carried on an iPad, instead of inside a knapsack, its purpose does not necessarily alter. So why should it enjoy a higher level of protection than its physical counterpart? Worse, why should a criminal escape detection merely because she decides to digitize illegal material? Does this not set up a reverse incentive?

Child pornography, nuclear weapon designs, and counterfeit currencies, for instance, are all expressly forbidden under customs laws.245 Why should the fact that a traveler carries them on an electronic device, instead of physically transporting a three dimensional representation, require the government to take additional steps to intercept it prior to importation? The materials encapsulate the same illegal behavior or threats. Shouldn’t there be a way to foreclose a digital end-run around the customs regime? By not allowing officials to access the cloud, there is a real risk that travelers can simply transfer contraband from their devices to the cloud prior to entering the U.S., only to later download it within domestic borders.

The strongest response to the equivalence argument centers on the search, similarly considering the function of the search in the contemporary context. It is not just digital contraband that is at stake once the Court allows the government to examine the mobile device or, through it, material held online. It is the traveler’s entire life, as well as significant amounts of others’ private affairs. It therefore is at once both intensely personal (as applied to that person and her family, friends, and acquaintances), and intrusive. While the search of a backpack, luggage, or shipping container might also reveal certain private matters, it does not in the process transmit the whole of a person’s life.

To the extent that electronic searches reveal information that would otherwise be held in the home, moreover, historic protections drop away, steadily narrowing rights. Email has replaced letter correspondence, electronic calendars now take the place of planners, and the contacts list now serves as a telephone book. The border exception, applied to electronic devices, threatens to swallow protections which, for centuries, have limited government power.

An approach that takes into account the broader context of the search performed on the digital device dovetails with Fourth Amendment jurisprudence. The Court regularly applies a totality-of-the-circumstances analysis to probable cause determinations.246 It uses it to determine reasonable suspicion.247 And it employs it to ascertain voluntariness in granting consent to search.248 In regard to electronic devices at the border, digital searches in which swathes of information becomes subject to government inspection changes the quality of the search itself. It is not the equivalent of looking in someone’s luggage.

The Court has already taken this position in regard to the search of electronic devices within U.S. borders. In Riley, it held that the government could not search a mobile phone incident to arrest because the quality of the search itself was different.249 The Court explained: “Cell phones . . . place vast quantities of personal information literally in the hands of individuals. A search of the information on a cell phone bears little resemblance to . . . physical search.”250 Because of this, the Court held that officers generally would be required to obtain a warrant.251

This also is the approach the Court has adopted regarding the border search exception writ large: the government cannot use the exception physically to search for undutied goods, contraband, and illegal entrants located on private property precisely because of the heightened privacy interests at stake. The founders were well aware of the dangers of allowing the government untrammeled access to individuals’ lives. The border exception was therefore tailored to the country’s sovereign interests in revenue generation and admitting qualified aliens, but it did not permit searches that went further afield.

And what of the end-run around customs by separating digital contraband from a particular traveler—for instance, by uploading it to the cloud, only to subsequently download it inside U.S. borders? Should Customs be able to access this information through the devices carried across international frontiers, potentially forcing the owners or users to provide passwords?

The first point to raise in response is that in-person physical transit has never been required for illegal goods to enter the country. The closest analogue would be use of the postal system. But as this Essay has explained, protections have been extended to the mail. A basic level of suspicion must be met to open sealed envelopes or packages of certain sizes.

A second point addresses the cloud concern: in a digital era, it is not only at ports of entry that the government has the opportunity to intercept digital contraband. Numerous laws, predicated on some level of individualized suspicion, provide an alternative means to access such materials. Law enforcement has the power to intercept wire, oral, and electronic communications related to a broad range of offenses, including all of those of interest to customs.252 For stored communications, the government can obtain a court order based on “specific and articulable facts showing that there are reasonable grounds to believe that the contents of a wire or electronic communication, or the records or other information sought, are relevant and material to an ongoing criminal investigation.”253 The order can be served on electronic communication or remote computing services.254 The government can also obtain stored communications 180 days old (or less) via a warrant.255 In 2016, changes to Rule 41 enabled agencies to obtain a warrant for remote access search and seizure of digital information.256

Foreign intelligence surveillance authorities also play a role in addressing international criminal conspiracies. In light of post-9/11 changes to the Foreign Intelligence Surveillance Act,257 and the infamous demise of the wall between foreign intelligence and criminal investigations, foreign intelligence laws are used to monitor international threats, even when the primary purpose of surveillance is criminal in nature.258 To the extent that provisions like the FISA Amendments Act do not apply, collection techniques consistent with Executive Order 12,333 may.259 In the context of non-U.S. persons, the government has even broader authorities.260

For digital data, as a matter of constitutional law, increasingly stringent requirements must be met for more invasive searches Because of the nature of electronic devices, no search can take place without, at a minimum, reasonable suspicion. The types of crimes to which such searches can be directed are only those explicitly authorized by Congress—not general criminal activity. For more invasive searches, probable cause and a warrant are required. Even here, the search must be appropriately circumscribed to avoid the type of general warrants prohibited by the Fourth Amendment.

B. Immigration

A second major challenge to this Essay’s argument could be raised regarding immigration. One might argue that part of the reason the government subjects noncitizens to searches prior to entering the United States is to ascertain whether they are who they purport to be, and what sorts of individuals are being admitted to the country. Surely, the type of information present in travelers’ electronic devices is relevant to such a determination. It could be considered irresponsible not to look at social media or the full range of an individual’s background—particularly where U.S. national security is on the line. Certainly, the powers of sovereignty undergirding the border exception provide adequate room for such examinations.

This is a strong argument. However, it does not apply to U.S. persons. Once a traveler establishes her identity as a citizen or legal resident, if there are no arrest alerts or other warrant notifications tied to the passport, there is no reason, under traditional immigration provisions, to commence a search. This is a bright-line rule. Probable cause must exist for a search of the person and, even then, it must meet the particularity required in the second clause of the Fourth Amendment.

The challenge thus applies solely to aliens. Here, as a constitutional matter, the government has more latitude than with regard to U.S. persons. Part of the function of the immigration services is to ascertain whether aliens admitted to the United States—either as visitors or as potential citizens—meet the policies set by Congress. As Chief Justice Rehnquist noted in Verdugo-Urquidez, a non-U.S. person lacking a substantial connection to the United States does not enjoy Fourth Amendment protections. To the extent, then, that the executive seeks to build profiles of non-U.S. persons entering or leaving the United States, the question appears primarily to be one of policy and statute, not one of constitutional law.

Nevertheless, as a constitutional matter, as well as an historical one, it remains for Congress, not the executive branch, to make this determination. An additional policy consideration is worth noting: in granting visitors access to the United States, the point at which background material would be most relevant is at the point at which a visa issues (at least for countries for which a visa is required). This suggests reviewing material at an earlier point in time, instead of focusing on the border crossing as an opportunity to look more carefully at those entering and leaving the United States. Whether or not this is a good idea in terms of the effect on U.S. foreign relations, or how U.S. citizens are treated in other countries, is a policy question. The decision of who and what to search, as applied to non-U.S. persons requires that Congress carefully consider myriad competing interests.


Many cases challenging the constitutionality of searches of electronic devices are beginning to move through the courts.261 In light of the significant Fourth Amendment issues at stake, this Essay has endeavored to explain the origins and evolution of the border search exception, which is justified only by its narrow purpose: the interdiction of contraband and the regulation of noncitizens entering the United States. In the process, it has argued that the nature of digitized searches differs in important respects from physical ones. Thus, while the transportation of digital contraband is still illegal, if the border search exception applies to electronic devices, the government’s use of it may be so broad as to render the Fourth Amendment obsolete. There is a reason that, in the past, the government was limited by geography and time, by the manner of transportation, the size of the item being inspected, the agency allowed to conduct the inspection, and the crimes for which they could interdict persons or materials. There are currently few, if any, equivalent border restrictions for digital contraband. Yet numerous alternative statutory instruments would allow for the interdiction of such materials.

As a matter of immigration law, as soon as a traveler establishes her identity as a U.S. citizen, the government must have probable cause, supported by a sufficiently particularized warrant, to search her electronic devices. Non-U.S. citizens lacking a substantial connection to the country are in a different constitutional category. Here, because of significant policy concerns, and Congress’s historic authority over immigration, the legislature has an important role to play. What is needed now, particularly post-Riley, Jones, and Carpenter, is a more careful approach, grounded in reasonable suspicion and probable cause, that is cognizant of the significant constitutional issues at stake in the inspection of travelers’ electronic devices.

Professor of Law, Georgetown Law. Special thanks to Jeremy McCabe at the Georgetown Law Library, who helped to obtain a number of the primary sources addressed in this Essay, as well as Grant Tanenbaum, for his research assistance. Professor Orin Kerr kindly provided comments. An early draft of this Essay was submitted, with the permission of the editors of Yale Law Journal, as written testimony to the U.S. Senate Committee on Homeland Security and Government Affairs’ Subcommittee on Federal Spending Oversight and Emergency Management. Hearing to Examine Warrantless Smartphone Searches at the Border: Hearing Before the Subcomm. on Fed. Spending Oversight & Emergency Mgmt. of the S. Comm. on Homeland Sec. & Governmental Affairs, 115th Cong. (2018) (statement of Laura K. Donohue).