American police are on trial now. This goes beyond Officer Derek Chauvin, who was recently convicted for murdering George Floyd in May 2020, for the entire institution remains under investigation. Much of our scrutiny has been rightly dedicated to thinking about excessive force and racial injustice, themes raised by Floyd’s murder and explored in some of my work. But while we’re thinking about policing, it may also be worthwhile to inspect some of its other features that are ripe for revision. One such feature is the Katz search doctrine.
Before we can discuss the doctrine, a little background is in order. American police are forbidden, by the Constitution, from conducting unreasonable searches of individuals or their things, at least if the individual or thing is within the United States. For this constitutional protection to mean anything, we must answer a key question first, “What is a search?”
The Katz search doctrine offers a partial answer to that question, albeit a wrong one. According to the doctrine, police search S (or S’s things) only if (1) S expects privacy with respect to the object of investigation and (2) it is reasonable to expect privacy with respect to that object of investigation. Sometimes, the doctrine returns intuitively correct results: for example, in the 1967 case that gives the doctrine its name, police used a listening device to eavesdrop on Charles Katz’s call on a payphone in a closed payphone booth. Katz was searched because yes, he expected privacy while on his call, and yes, it generally seems reasonable to expect the details of a conversation to be private when one closes the booth’s door. Once the US Supreme Court determined that Katz was searched, it was pretty easy to find this search to be an unconstitutional unreasonable search because it was not licensed by a search warrant. Of course, if the eavesdropping had not been a search, police would have needed no search warrant.
To me, the troubling part of the Katz doctrine concerns Prong 1, the contention that it doesn’t make sense to say that somebody has been searched when the person didn’t expect the object of the alleged search to be private in the first place. This Prong seems fitting sometimes. If, for instance, Mr. Katz had the payphone booth wide open and was screaming at the top of his lungs, it seems wrongheaded to claim that, in overhearing the conversation, police searched him. Ultimately, Prong 1 of Katz is subject to counterexamples because our expectations of privacy are manipulable.
I am not the first person to raise this worry. Going back to the 1970s, critics have worried that government might be able to manipulate our expectations of privacy. In particular, government might lower our expectations of privacy and thereby bootstrap its way into making police conduct not a search. For example, suppose the police hang a sign in a park, and the sign reads, “All bags will be subject to inspection!” It is hard to say, after reading this sign, that one expects the contents of one’s bags to remain private. According to Prong 1 of the Katz doctrine, inspection of one’s bags in that scenario is unlikely to be a search and thus is unlikely to require any search warrant. Prong 1 then has two problems. It does not track anyone’s pre-theoretical understanding of a search, and it licenses more unchecked police surveillance.
Cases in which government manipulates our expectations and then relies on those changed expectations to subject new activity to unchecked surveillance – this is sometimes called Katz circularity. Some recent empirical work claims that Katz circularity does not, in fact, exist. According to this research, people’s expectations of privacy are not easily changed by government actions. Like a good philosopher, I won’t weigh in on this disputed question of fact. There are other ways that our expectations of privacy can be manipulated, and new counterexamples can show this.
Private actors often announce that they will track typically private information: employers monitor employee emails, websites track users’ online activity, tech companies monitor geospatial location. If police get access to these emails, online activity, or location information, can we honestly say that we expected all of this to be private? If not, acquiring the information is not a search, under the Katz doctrine.
One’s expectations of privacy can be lowered, even when no one sets out to do so. Perhaps a person develops paranoid personality disorder and comes to believe that many people are spying on her. Perhaps a person is a small child, who has been subject to lots of surveillance because, frankly, that’s what good parenting involves. These and other people might have little expectation of privacy, and yet it would be misguided to think that such people cannot be searched and equally misguided to allow police to exploit these reduced expectations of privacy.
The discussion, thus far, has been a little hypothetical. Here’s a real case where the rubber hits the road. Antoine Jones was a driving his wife’s car, but little did he or the wife know, police had placed a GPS tracker on the car. Police then tracked his movements for a month, trying to gather evidence for a drug trafficking case. The government argued that following Jones’s movements on the public roads could not be a search. How could one expect one’s movements on public roads to be private?! Obviously, at one level of description, Jones expected privacy, but at another, he likely didn’t. When this case reached the Supreme Court, it decided to add a new sufficient condition for a search: if police trespass on your property with investigatory intent, it is a search. Placing the GPS tracker was a trespass, so Jones was searched. Of course, if police had merely tailed Jones’s car for a month, that would’ve been fine, so far as the Court majority was concerned.
The Jones case, despite that last bit, moves us closer to what I have endorsed in other work. We must de-couple actual expectations of privacy from the question of whether someone has been subject to a police search. As I would have it, someone is subject to search if the object of investigation is something society should guard from police surveillance.
I’ll close with saying something to those who think they don’t care so much about privacy or the Socratic question “What is a search?” It may seem like these are lawyerly matters for which those concerned with broader questions of justice need not to be concerned. Indeed, when activists are calling for police abolition, a circumscribed conversation about the contours of police surveillance practices can seem ho-hum. I have two responses. First, curtailing police surveillance may be a good start to curtailing other police practices. Second, in an America where policing persists – whether or not that’s a second-best world – philosophers and other intellectuals will need to roll up our sleeves and get into the messy details. We’ll need to talk about police searches, about no-knock warrants, about qualified immunity, about the rise of algorithmic policing. Sexy hot-takes must give way to careful reflection on a complicated institution.
Raff Donelson
Raff Donelson (@RaffDonelson) is an Assistant Professor of Law at Penn State Dickinson Law. His current research focuses on criminal justice, analytic jurisprudence, and metaethics. His latest article is "Natural Punishment."
