The joined cases of Riley v. California and United States v. Wurie rightly have been hailed as a ringing endorsement of privacy in the digital age.  By holding that police may not search the contents of a cellphone upon arresting a suspect without first obtaining a search warrant, the Supreme Court worked a substantial change in the law.  And in recognizing that “digital is different,” the High Court potentially began to question areas of law in which digital technologies had been treated as mere changes in degree, rather than changes in kind, from their analog predecessors.

But a change in the general approach of courts to digital searches will face a few headwinds that can also be found within the opinion itself.  Indeed, the reach of the Riley decision may not stretch quite as far as the most generous reading of the opinion may suggest (and, moreover, may not mark a significant departure from the current practice of federal prosecutors and law enforcement officers, many of whom were accustomed to obtaining search warrants in the kinds of circumstances that led to the Riley case).

This is so for two main reasons:  First, despite the expansive language in the opinion about the ways in which new technologies contain panoptic insights into our private lives, the holding rests pretty narrowly on the logic of the “search incident to arrest” doctrine.  In this vein, Chief Justice Roberts, in a footnote to the opinion, explicitly notes that the Riley decision does “not implicate the question whether the collection or inspection of aggregated digital information amounts to a search under other circumstances.”  Second, other language in the decision indicates the Court’s preference for clear, easily administrable lines in the criminal law context, suggesting that the Court may not (yet) be ready to completely do away with other areas in which digital rights have not yet caught up with digital technology, such as the much-maligned third party doctrine. 

The search incident to arrest doctrine holds that arresting police officers are entitled to search objects that are on the person of an arrestee or within his immediate reach at the time he is taken into custody.  And the rationale for the rule is fairly clear:  Officers are entitled to conduct the search at the time of arrest, when the suspect’s privacy rights are diminished, in order to ensure their own safety and/or to guard against the destruction of evidence.

And it is both the limits and the purposes of this doctrine that formed the basis for the holding of the Riley case.  The court ruled that except for very specific circumstances (e.g. a razor blade hidden within a cell phone), ensuring the safety of the arresting officer will not require a search of the phone, and certainly will not require a search of its digital contents.  So too are the fears of suspects destroying digital evidence diminished once arrestees and their cell phones are under the control of the officers.  If neither of these rationales hold in the context of cell phone searches incident to arrest, then neither does the rationale for permitting such searches without a warrant.

In short, cell phones, which really are “minicomputers that also happen to have the capacity to be used as a telephone,” contain substantially more information implicating the most sensitive details of our private lives than the physical evidence that usually is obtained from searches incident to arrest.  And now the law, rightfully, treats such technological repositories on their own terms, rather than simply shoehorning them into established categories imported from the analog world.

But the relationship between advanced technology and law enforcement does not inevitably or invariably lead to enhanced privacy protections.  The Court also identifies the flip side of advanced technology—that digital developments also can be used to more effectively realize the purposes of law enforcement.  The Court demonstrated that technology, in other words, can be used as a sword as well as a shield in the context of searches of digital devices.

The majority opinion of Chief Justice Roberts raised two specific examples of instances in which technological advances facilitate the ability of law enforcement to obtain access to the digital evidence it needs.  The first is the use of “Faraday Bags,” which are enclosures that isolate mobile phones and other devices from radio waves, thereby preventing arrestees or their confederates from “remotely wiping” the data on their devices.  Developments like this provided the Court with the rationale for holding that the search incident to arrest doctrine does not apply to cell phones (if the police can preserve the contents of the phone cheaply and easily, fears about losing access to evidence that animate the doctrine are diminished).  But devices like Faraday bags also give law enforcement the ability to preserve and exploit digital evidence for longer periods of time.  The opinion of Chief Justice Roberts also referenced the practice of digital warrant applications, in which police officers can email warrant applications to judges’ iPads and receive responses in “less than 15 minutes.”

The proliferation of advanced technology that aggregates personal information may therefore expand the number of instances in which law enforcement is required to obtain a warrant, but the Court also acknowledged that technological developments make those warrants easier and more efficient to obtain.  Advanced communications technology also presumably puts more information about suspects into the hands of law enforcement officers in the first instance, facilitating the accumulation of evidence that will meet the probable cause standard.

A second feature of the opinion may also slightly complicate the rapid expansion of Riley’s reasoning and language to other areas of the law, particularly the third party doctrine.  The third party doctrine generally holds that information voluntarily provided to third parties, such as telephone numbers that people dial, loses its constitutional protection.  While the doctrine has been roundly criticized for permitting far too much private information to become available to law enforcement without a search warrant, one valuable feature of the third party rule is that it is (relatively) easy for the 18,000 state and local law enforcement agencies in this country to administer.

The affirmation of the Court in Riley that it has a “general preference to provide clear guidance to law enforcement through categorical rules” may, therefore, signal that it is not quite ready to abandon rules like the third party doctrine.  In the Riley case, the general preference for clear rules worked to the advantage of digital privacy, giving the Court a rationale for rejecting the government’s proposed rules that would have permitted warrantless cell phone searches in some circumstances, but would have denied such searches in other cases.  But one can easily envision cases in which the preference will not always cut in the direction of greater privacy protection.

An alternative view of privacy protection would not treat “privacy as an on/off concept that is forfeited once any amount of sharing of information takes place, or once an individual is in the public sphere.”  It would, rather, evaluate acts or programs of collecting, processing, disseminating, and using personal data on their own terms for the purposes of constitutional analysis.  In this alternative conception of privacy, the collection and aggregation of large amounts of data about individuals from many sources, any or all of which might be public, would amount to a privacy intrusion in its own right.  In lengthy sections of the Court’s opinion in Riley, Chief Justice Roberts did not engage in a mechanical application of the search incident to arrest doctrine, instead analyzing the ways in which the digital privacy characteristics of the specific items searched affected the application of a well-established legal rule.  And this, in some respects, is what the concurring opinions in U.S. v. Jones advocated as well, with Justice Sotomayor taking into account the specific attributes of GPS monitoring “when considering the existence of a reasonable societal expectation of privacy in the sum of one’s public movements.”

But such context-specific determinations of whether particular forms of data merit constitutional protection may be in some tension with the language of the Court indicating a preference for clear rules, particularly in a world in which the kinds of data that we all generate and the methods available to analyze that data constantly are changing and expanding.  Which one of these two views—context-specific analyses of the privacy implications of police activity, or the preference for clear easily-administrable rules—will prevail will only be determined with time.  And indeed, future Courts considering similar cases may find a way to combine context-specific privacy protections with clear predictable rules that can be used ex ante to guide the behavior of law enforcement.  But whichever view prevails, the Riley decision will have moved forward a very important conversation about the ways in which the law treats the implications of advanced technologies for privacy rights.