My FindLaw column for this week (available here) discusses a recent decision from the New York Court of Appeals (New York's highest court), holding that police must have a warrant, supported by probable cause, before attaching a GPS device to a suspect's car and thereby remotely monitoring the suspect's travels. The state court's ruling rests entirely on New York State constitutional law -- its analogue to the Fourth Amendment right against unreasonable searches and seizures. In my column, I discuss the implications of avoiding the federal constitutional question while simultaneously distinguishing the facts of People v. Weaver (involving a GPS device) from the facts of the most factually similar federal precedent, United States v. Knotts (involving a primitive "beeper" tracking device).
In this post, I want to focus on a different question. If -- as the dissenters in Weaver argue -- the GPS device is really no different from police watching us from the street, does this similarity legitimate unregulated use of GPS devices or does it instead raise questions about unregulated public visual surveillance?
The first question the reader might have is this: Why does it even matter whether the police use of a GPS to track us is like police watching us on the public streets? It matters because when police do something to us that any private person can and will also do to us routinely, then the police have not invaded our privacy in a meaningful way and therefore do not need a warrant or probable cause to act. Police need not turn away from what everyone else can see.
To give an example, if I yell an incriminating secret to my friend on a subway train, I have no "reasonable expectation of privacy" in the yelled statement. Anyone on the train can easily hear what I said (and indeed, many may be unable to avoid hearing what I said, even if they would prefer to read the newspaper and tune me out). Therefore, a police officer may also listen to what I am saying without having first to develop reasonable suspicion of me or otherwise lay the groundwork for performing a search. To put it differently, if I "knowingly expose" personal information by yelling it out in public, I forfeit any interest that I had in concealing that information from the police, just as I plainly forfeit my interest in keeping it secret from the private people who happen to be riding the train.
The U.S. Supreme Court has said that a police officer may follow people along the public streets (by foot or in a vehicle) without compromising anyone's reasonable expectation of privacy. A pursuit is thus not a search or seizure subject to the Fourth Amendment's requirements. This is because, according to the Court, your comings and goings in public are in no sense "private": anyone who happens to be on the street can see you going from place 1 (e.g., a psychiatrist's office) to place 2 (e.g., a strip club) and then to place 3 (e.g., an abortion clinic). You do not have privacy in public because you voluntarily and knowingly convey the information about where you are simply by appearing in public.
If this is true, and if we assume that a GPS device benignly increases the efficiency of the public vantage point that police would otherwise have, then it follows that attaching a GPS device to your car does not compromise your Fourth Amendment right against unreasonable search and seizure and need not be justified with suspicion or a warrant.
I would, however, challenge the notion that it is acceptable -- for police or for private citizens -- to follow you around and "observe" where you go in your daily travels. It is one thing if an officer or a neighbor happens to see you on the street (and thereby learn that you visit an "adult" book store, for example). It is quite another for an officer (or neighbor) to walk or drive behind you at a distance over long periods of time and make these same observations. In such a case, you are the target of surveillance. Such targeted following will likely feel quite different, if you were to learn of it, from the occasional "fancy meeting you here!" situation. It feels less like an accidental exposure, in other words, than like a deliberate invasion of privacy.
When a private individual follows you around, for instance, we might call such an activity "stalking," and you might be able to get a restraining order against the private individual to prevent him from continuing his personal tracking. It is therefore unclear why, when a police officer does it, he or she should be exempt from the norms that render such behavior legally questionable among private actors. And this is true even without the increased efficiency and power of a global positioning device tracking your every move.
The U.S. Supreme Court has long made a dubious assumption about exposure -- that if you take a risk that exposure might occur, you have thereby "knowingly" exposed yourself to the public. In California v. Greenwood, for example, the Supreme Court held that police may rummage through the garbage you leave outside for collection, without a warrant, without probable cause, and without any sort of reasonable suspicion of finding incriminating materials there. The reason the Court gave for characterizing garbage rummaging as something other than a "search" was that young children or animals or "snoops" might tear open your garbage after you leave it out, and you therefore assume the risk that the contents of an otherwise opaque container will become visually available for all to see (even when no human or animal actually tears it open).
One flaw here is clear when we note that putting out the garbage in no way "invites" such intrusions, some of which are either unusual or downright illegal (as I discuss in greater detail in an article in the Stanford Law Review (v. 55, p. 119), entitled What is a Search? Two Conceptual Flaws in Fourth Amendment Doctrine and Some Hints of a Remedy).
It is not normal, everyday conduct to follow people around and observe where they go throughout the day. When you leave the house, you do -- of course -- risk that at any given time, you will be seen by someone you know (and find yourself embarrassed to have been "discovered" in a particular place). But this risk does not entitle anyone to follow you (rather than coincidentally to run into you sometimes), and it accordingly should not entitle the police to do so -- with or without the aid of a GPS -- if the police can demonstrate no reason for invading your privacy. The fact that going out in public risks exposure is morally no different from the fact that leaving the door of your house open risks theft -- in neither case have you legitimated the unlawful acts that might follow.
Posted by Sherry F. Colb