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Could Better Technology Lead to Stronger 4th Amendment Privacy Protections?

Scholar Orin Kerr explores how the reshuffled Supreme Court might rule on surveillance and policing.

April 6, 2022
Close-up shot of hands using a cell phone

Amendment IV

The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no Warrants shall issue, but upon probable cause, supported by Oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized.

Judges, defense lawyers, police and prosecutors have been fighting over the Fourth Amendment for 230 years, and it’s not hard to figure out why. So many of the words in the text are vague. “Houses, papers, and effects,” for example, means more today than they did when James Madison drafted the Bill of Rights. So, too, does the clause “things to be seized.” What things? Seized how and by whom? Only “unreasonable” searches and seizures were barred, remember, leaving it up to future courts to argue over what is and what is not a “reasonable” exercise of police power.

Madison and company knew that some of the ambiguities contained in the Bill of Rights were necessary to achieve the political compromise necessary to ensure ratification of a document that changed the way the U.S. government interacts with citizens. The drafters also knew that by these ambiguities, they were passing on tough definitional questions to future judges and legislators to figure out. The same thing happens today, by the way, when Congress enacts ambiguous legislation and then complains that federal judges aren’t interpreting it properly. The late Supreme Court justice Antonin Scalia used to complain about that all the time.

The justices over the centuries have developed a series of standards they’ve used to determine when a search is a search under the Fourth Amendment and then whether such a search is “reasonable.” And because technology has ceaselessly evolved over the generations — police once searched for written letters and diaries, now they also search for emails and text messages — Fourth Amendment standards have evolved as well. The law is always catching up to technology, and the speed with which it catches up usually is determined by the Supreme Court or Congress.

For some answers about these standards, I turned to Orin Kerr, author and professor at UC Berkeley School of Law. Kerr is known for his scholarship on criminal procedure in general and the Fourth Amendment and computer crimes in particular, and he’s frequently at the center of legal and political debates at the intersection of technology and privacy rights.

COHEN: There is often great frustration over the willy-nilly way judges seem to interpret and enforce Fourth Amendment protections. You wrote a really interesting Harvard Law Review article in 2011 in which you described an “equilibrium adjustment” theory of the Fourth Amendment. “The Supreme Court adjusts the scope of Fourth Amendment protection in response to new facts in order to restore the status quo level of protection,” you wrote. “When changing technology or social practice expands government power, the Supreme Court tightens Fourth Amendment protection; when it threatens government power, the Supreme Court loosens constitutional protection.”

A decade later, how has your theory held up? Have the Supreme Court and lower courts done more to harmonize what some see as cognitive dissonance at the heart of Fourth Amendment jurisprudence, or has the law grown muddier? 

KERR: I think my theory has held up well. Two of the biggest Fourth Amendment cases in the last decade are Riley v. California and Carpenter v. United States, and that’s exactly what the Supreme Court did in those two cases. In Riley, the Supreme Court held that the search-incident-to-arrest exception doesn’t apply to cell phones. The government can always search physical property on a person at the time of arrest, the Court has long held, but under Riley the government needs a warrant to search a cell phone then. That new rule was needed, the Court said, because applying the old rule to new technology no longer made sense: Applying “that reasoning to digital data has to rest on its own bottom.”

Similarly, in Carpenter, the Court held that the Fourth Amendment protects historical cell-site location records. This was needed despite the older cases pointing to the opposite result, the Court reasoned, to “assure preservation of that degree of privacy against government that existed when the Fourth Amendment was adopted." New technology of cell phones gave the government access to a new surveillance method, and the Court had to change the old legal rule to ensure that the government didn’t have too much power.

Of course, some would still find the law muddled. Some might say that Riley and Carpenter made the law more muddled than before. But I would say the law is just really fact specific. How the Fourth Amendment applies depends on the facts, and you have to read a lot of cases to understand what the rules are.

COHEN: Riley v. California was decided in 2014 when Justices Antonin Scalia, Anthony Kennedy, Ruth Bader Ginsburg, and Stephen Breyer were on the Court. They are all gone or about to be gone now. Carpenter v. United States was decided in 2018 and the majority opinion in that case included two justices (Ginsburg and Breyer) who are gone or who will soon be gone from the court. What’s your sense of how the three Trump-nominated justices will push or pull Fourth Amendment law in one direction or another? For that matter, what’s your sense of what a Justice Ketanji Brown Jackson would bring to the debate over the Fourth Amendment? Have you had a chance to compare her views with those of Justice Breyer, the man she would replace?

KERR: The overall effect of these newer justices is mixed, and it probably depends on the specific doctrine. But I can try to offer an overall take just by running through the new justices. First, Justice Brett Kavanaugh tended to be on the government’s side in Fourth Amendment cases back when he was on the DC Circuit, but then he was the fifth vote (together with Chief John Roberts, Breyer, Elena Kagan, and Sonia Sotomayor) for the plaintiff in last term’s significant Fourth Amendment case, Torres v. Madrid. Second, Justice Neil Gorsuch has a significant libertarian streak, which you can see in his separate opinion in Carpenter, but he can also end up on the government’s side in divided cases (as he did in Torres).

It’s too early to tell how Justice Amy Coney Barrett will be in the Fourth Amendment area. Finally, I expect Ketanji Brown Jackson will favor considerably more expansive Fourth Amendment rights than did Breyer, who was a swing vote in Fourth Amendment cases. Jackson is likely to be pretty different. She’s a former public defender, and I would guess she will join Sotomayor (and perhaps go beyond her) in being most likely to disagree with the government in Fourth Amendment cases. 

In terms of what these new justices will mean for Fourth Amendment litigation generally, I expect many more Fourth Amendment cases will be briefed to the justices using originalist arguments. Briefs tend to be written to the “swing vote,” the justice who is needed to secure a majority and therefore a victory. We don’t quite know who the center votes will be in Fourth Amendment cases, but Justices Barrett, Gorsuch, Kavanaugh, and Roberts are all possibilities. I suspect we’ll see a lot of originalist arguments being made in Fourth Amendment cases to try to persuade those justices. 

COHEN: You wrote a detailed analysis about a first-of-its-kind ruling on geofence warrants and their application to Fourth Amendment law. Geofencing involves the use of GPS technology to create a geographic boundary that allows police, relying on Google for example, to track a cell phone user’s location. The case is out of Virginia, U.S. v. Chatrie, in which a federal judge suppressed the results of a police search warrant because the warrant gathered geofencing data from a wide swath of people who could not possibly have any relationship to a nearby robbery officers were investigating. The complicated decision raises questions not just about what privacy expectations people have in the age of location-tracking on cell phones but whether new technology justifies a new way to approach Fourth Amendment jurisprudence more broadly.

You were skeptical of the judge’s analysis, and you suggest that such searches may not even be subject to Fourth Amendment protections in the first place, but I was struck by what you wrote toward the end of your piece: “One wonders if the possibility that technology can enable the execution of warrants in a more privacy protective way than traditional warrants is leading [U.S. District Judge M. Hannah] Lauck to in effect seek a new Fourth Amendment standard that requires warrants to be executed in the most privacy protective way the new technology allows.”

Can technology at last push Fourth Amendment law to a tipping point where federal judges start looking for new standards to guide their decisions? I suspect you’ll say that no matter what, these cases will necessarily be fact-specific, but is there a point where the government’s use of new surveillance technology forces changes in the legal standards to which those facts will be applied? And if so, do you have a sense of which justices on the court would be most willing to entertain such a change?

KERR: I think there are two different questions. First, can technology so expand government power that the Supreme Court will adjust Fourth Amendment rules to limit government power? My answer to that is yes, and that is the basic idea of equilibrium-adjustment that we have been discussing. In the blog post, though, I was addressing a different question: If technology permits the government to access information but also creates the prospect of newer and better privacy protections than have existed before, should the Fourth Amendment require those new greater privacy protections?

That’s part of what’s interesting about geofencing warrants, I think. Google can try to get the government to execute those warrants in a more privacy protective way than warrants have been executed previously. Traditionally, search warrants are executed in a brutal fashion: The government breaks in, rifles through everything, and sees everything. It’s a severe privacy violation. In contrast, Google can (and wants) to carefully screen information from the government, limiting what the government can see and limiting the identifying information about whose account it is seeing. The question is, if technology creates new ways to protect privacy, should the law impose that requirement?

As to what the Supreme Court might say to that, the signals are mixed. On one hand, in a case like Missouri v. McNeely, the Court suggested that the ready availability of telephone warrants these days might make the warrant requirement broader. As warrants become easier to get, the thinking runs, it becomes less burdensome to impose a warrant requirement. That’s not exactly the same. But it’s a little bit similar, I think. On the other hand, the Court has repeatedly rejected any kind of “least intrusive means” search requirement under the Fourth Amendment. And that cuts the other way.

COHEN: I want to go back to the Torres case for a second because it addresses, or tries to address, the Fourth Amendment’s approach to police use-of-force cases, a topic near and dear to my heart. Torres had to do with whether a suspect was “seized” within the meaning of the Fourth Amendment when an officer tries but fails to subdue that suspect. And the Supreme Court ruled that the attempt alone to seize a suspect — in that case officers firing at a woman fleeing in her car — triggered a Fourth Amendment analysis. We’re living in an era where there are more lawsuits alleging excessive force by police officers, and certainly more taxpayer-funded legal settlements paid by police officials, and I’m wondering whether you are seeing the effects of these cases in Fourth Amendment law. In other words, how is police reform shaping Fourth Amendment law?

KERR: It’s hard to tell, as we can’t answer the counterfactual of what the law would look like otherwise. But I’m skeptical that police reforms are shaping Fourth Amendment law. George Floyd was killed in May 2020. Since then, the Supreme Court has agreed to hear zero new Fourth Amendment cases. That’s remarkable. In a typical term, the Supreme Court hears three or four Fourth Amendment cases. This term, for the first time I can recall, it isn’t deciding any Fourth Amendment cases at all. The Court has also turned away a series of petitions asking it to overturn qualified immunity, the judge-made legal doctrine used to shield police officers, corrections officials, and others from liability for their misconduct. Justice Thomas has written dissents from denials of certiorari on this, as he wants the Court to reconsider qualified immunity. But the rest of the Court has been silent. It’s hard to know, but renewed interest in police reforms might be making the justices less likely to step in themselves. They may be waiting for the elected branches to act. But this is all just speculation. Unfortunately, we don’t know.

COHEN: Let’s end by looking ahead. We know that there will be technological advances in the next decade that will affect Fourth Amendment law. There always are. Does anything in particular stand out to you as something to watch in the years ahead? Do you see the law and technology careening toward some flashpoint?

KERR: I don’t think there will be flashpoints, but I’m expecting continued evolution. The lower courts are disagreeing on a lot of Fourth Amendment issues involving technology, and that will likely prompt Supreme Court review in the next few years on those issues. The Supreme Court will probably decide how the Fourth Amendment applies to long-term pole camera surveillance, if it allows warrantless border searches of computers, how the private search reconstruction doctrine (which allows the police to view the results of warrantless online searches by private parties) applies to internet providers; what the limits of computer warrants are, and, in the Fifth Amendment area, when the government can force people to unlock their phones. As always, stay tuned!

This interview has been edited for length and clarity.

This discussion is one of several in a Brennan Center series on the Bill of Rights. The interview with David Carroll about the Sixth Amendment is here, and the interview with Carol Steiker on the Eighth Amendment is here.