At the end of last term, the U.S. Supreme Court in Carpenter v. United States, 138 S. Ct. 2206 (2018), hammered a bit deeper the wedge it had previously inserted between electronic evidence and non-electronic evidence under the Fourth Amendment.
As the high court has said time and again, "[t]he touchstone of the Fourth Amendment is reasonableness." United States v. Knights, 534 U.S. 112, 118 (2001). In recent years, however, the court has started to recognize that what is reasonable for non-digital evidence may not be reasonable for digital evidence.
This partial remodel of the Fourth Amendment started less than a decade ago.
Prior to Riley v. California, 134 S. Ct. 2473 (2014), police could conduct a thorough search of an arrestee and the area within his "wingspan" without any "additional justification" as long as the arrest itself was lawful. United States v. Robinson, 414 U.S. 218, 235 (1973). Riley limited that rule to non-electronic evidence by creating a new rule for cellphones and other electronic devices: Police can seize those devices when conducting a search but, absent exigency or some other exception to the warrant requirement, cannot search them without a warrant. Riley, at 2485.
Prior to Carpenter, police could use a beeper to track a person's movements on public streets without a warrant. United States v. Knotts, 460 U.S. 276, 281-82 (1983); cf. United States v. Karo, 468 U.S. 705, 714-16 (1984) (tracking devices may not be used for movement on private property). And police could obtain records pertaining to a person that were held by third parties without a warrant. United States v. Miller, 425 U.S. 435, 440-43 (1976) (banking transactions); Smith v. Maryland, 442 U.S. 735, 742-43 (1979) (numbers dialing into and out of a particular phone). The rationale for both rules was basically the same: A person has no "reasonable expectation of privacy" in activities or information he exposes to others such as her movements on public streets or her transactions with third parties. Carpenter limited both rules to non-electronic evidence by creating a new rule applying to the locational data for a cellphone held by third-party cellphone providers: Police can obtain this data only if they first obtain a warrant. Carpenter, at 2217-19.
Even the legislative branch is doing some touch-ups to statutes governing the procedures for obtaining evidence. In 2016, the California Legislature enacted the California Electronic Communications Privacy Act (or CalECPA, for short). Among other things, CalECPA specifies that police may obtain "electronic communications information" from a third-party "service provider" only if they first obtain a special type of search warrant that lists "the types of information sought" and, critically, limits them to seizing information "related to the object of the warrant"; to continue searching for any information beyond that originally sought, CalECPA specifies, the police need a follow-on warrant. Penal Code Section 1546.1(b)(1), (d)(1), (d)(2). In essence, CalECPA eliminates for electronic evidence -- but not for non-electronic evidence -- the "plain view" doctrine that otherwise permits police to seize any evidence they happen upon while conducting a search for something else as long as that evidence's "incriminating character" is "immediately apparent." Horton v. California, 496 U.S. 128, 136-37 (1990). The 9th U.S. Circuit Court of Appeals has voiced similar concerns about applying the plain view doctrine to electronic searches. E.g., United States v. Comprehensive Drug Testing, Inc., 621 F.3d 1162, 1176-77 (9th Cir. 2010).
The justification for this differential treatment seems to follow a consistent blueprint: Digital evidence is different, both in quantity and quality: Electronic devices store or generate far greater volumes of data, and that data often "provides an intimate window into a person's life." Riley, at 2489-90; Carpenter, at 2217. Putting a tail on a suspect is expensive and time-consuming, but placing a GPS device on his SUV can reveal, with little effort or expense, his every movement (whether it be to the International House of Pancakes or the House of the Rising Sun).
The net result is a "digital divide" -- that is, two sets of rules for obtaining evidence, one that applies to digital evidence and the other that applies to non-digital evidence.
Rather than plumb whether this divide should have been created, it may be more useful -- particularly in light of its persistence -- to ask what effect it might have going forward.
The law of criminal procedure sometimes rests on the notion that criminals are rational actors. The ex post facto clause of the U.S. Constitution, for instance, prohibits a legislature from retroactively increasing a crime's punishment because doing so robs a defendant of "fair notice" of the consequences of his contemplated crime. E.g., Aponte v. Gomez, 993 F.2d 705, 708-09 (9th Cir. 1993).
If the law assumes that a defendant thinks through the consequences of his crime in advance, why shouldn't the law also assume a person will think through how to commit his crime in advance and will choose a method of doing so that makes it easier for him to get away with it? A savvy drug dealer aware of Riley would most certainly elect to keep his pay-and-owe ledger in an Excel spreadsheet accessible through his cellphone rather than inside a paper notebook he carries around in his pocket. See "Comprehensive Drug Testing," at 1176 ("Wrongdoers and their collaborators have obvious incentives to make data difficult to find").
The incentives to commit crimes using electronic devices will exist as long as those devices are accorded greater protection from law enforcement than their non-digital counterparts -- that is, as long as a digital device persists under the Fourth Amendment.
The next questions then become: Should courts consider this particular consequence of the digital divide? And, to eliminate those consequences, should the courts eliminate the divide itself (ostensibly, by adopting the same protective rules for digital and non-digital evidence)?
It is difficult to hit these specific nails on the head.
At times, the U.S. Supreme Court has carved an exception into an existing rule, noted that the exception creates a "fine line," and ruled that its "formalism" was nevertheless justified. When it comes to obtaining consent to search a residence, the consent of any co-occupant generally suffices, United States v. Matlock, 415 U.S. 164, 170 (1974), unless, as the court subsequently held in Georgia v. Randolph, 547 U.S. 103 (2006), another co-occupant is at the door objecting. Although Randolph bars the police from "remov[ing] the potentially objecting tenant from the entrance for the sake of avoiding a possible objection," Randolph, at 121-22, nothing in Randolph precludes police from simply waiting for the likely naysayer to leave on his own, and this "fine line" Randolph draws would seem to give police the incentive to do just that.
Other times, the high court has carved an exception into an existing rule, for a time upheld the "distinction" it created, but ultimately allowed the exception to swallow the rule. In Harris v. United States, 536 U.S. 545 (2002), the court ruled that the requirement (from Apprendi v. New Jersey, 530 U.S. 466, 490 (2000)) that any fact that "increases the penalty for a crime beyond the prescribed statutory maximum" be submitted to a jury and proved beyond a reasonable doubt did not apply to facts that trigger a mandatory minimum sentence. A decade later, in Alleyne v. United States, 570 U.S. 99, 111-12 (2013), the court eliminated this distinction -- and, as a result, abolished any incentive it had created for state legislatures to fiddle with mandatory minimums rather than to touch the maximum sentence -- by making Apprendi's rule applicable to mandatory minimums as well. Id. at 113.
It is far too early to know whether the U.S. Supreme Court will continue to carve out more "digital only" exceptions to its prior Fourth Amendment precedent, or whether it will someday determine that the incentives arising from the deepening digital divide, along with other considerations, so weaken the foundation of the non-digital precedent that it collapses under its own weight.
Because courts decide cases one at a time, the blueprint is being assembled as each brick is added to the wall of precedent; the architect and the builder are one and the same. Thus, the fate of digital divide will arrive in the same manner as its creation -- one case at a time.