By Sherry F. Colb
In my FindLaw column for this week, I discuss the D.C. Circuit case of United States v. Maynard, in which the court held that police must adhere to Fourth Amendment "reasonable search" requirements when using a GPS device to monitor the location of a target's vehicle 24/7 for a month. The column considers the viability of this holding, part of a circuit split, once the Supreme Court takes the question whether GPS monitoring qualifies as a "search" falling within the protection of the Fourth Amendment. The D.C. Circuit's theory is that unlike people on the street (who can see your car out in public), no individual in public will -- in the absence of GPS technology -- be in a position to observe all of your comings and goings in your car. Such observation enables an understanding of your routines, and departures from those routines, that conveys far more information about you than the discrete snippets available for public viewing when you venture out in your car.
In this post, I want to consider respects in which GPS monitoring might actually be less intrusive than an analogous viewing in public by police. That is, although the GPS provides far more (and more thorough) information about you than someone driving behind you on the roads would be privy to, there are also ways in which being followed is worse than having one's movements tracked by GPS device, all other things being equal, although, of course, they are not.
First, when police follow you (as opposed to tracking you via a GPS), they can see you and therefore see what you do while in your car, whether you place anything in your trunk, and whether you take passengers, either from the beginning of the journey or in the course of your travels. A GPS will not give police any of this information. If one were given the choice, then, of being followed by police all of the time while in one's car, or being tracked with a GPS, one might well prefer the latter to the former.
Second, when police follow a person, the person can see the police in pursuit. This "transparency" has the advantage of allowing the person to act in a way in which she feels comfortable acting in front of a watcher. On the other hand, and for similar reasons, this transparency is also quite inhibiting and potentially intimidating. Where you might otherwise have played music and sung along with your radio, you could now worry about how this might appear to the police behind you and leave the radio off. Where you might have stopped your car at the corner and handed money to a homeless person, you could now worry that this would appear to be some sort of illegal transaction. And where you might have given your companion a kiss at the red light, you could feel uncomfortable about doing that in front of the police. Finally, you might feel a sense of constant anxiety about whether the police will, mistakenly (or perhaps correctly) believe that you are acting in violation of the myriad traffic laws that apply on the road. Installation of a GPS device on your car would have few of these effects. In this sense, your ignorance of the surveillance might represent bliss.
Third, if police were to follow you, neighbors and others in the vicinity of your car might well assume that you have done something to trigger the officers' suspicion (despite the fact that police need not have any suspicion at all to justify their following you, as a matter of Fourth Amendment law). This could be quite humiliating even if only strangers are in a position to watch, and might damage your reputation in the community, if people recognize the person being followed as you. To the extent that you enjoy anonymity in your car, a police "escort" of this sort singles you out for derision. For this reason, for example, although the Supreme Court considers home arrests more intrusive than public arrests (and therefore requires an arrest warrant only for the former but not the latter), some people would doubtless prefer to be arrested in the privacy of their own home rather than in full view of every person, stranger and acquaintance, walking down the street at the time.
As I said above, of course, all things are not equal, and the police do not have the resources to place a constant tail on people for no reason. GPS monitoring, on the other hand, is quite cheap and therefore requires little sacrifice or resource allocation by the police. As a result, as a practical matter, police will generally not be in a position to follow people physically for extensive periods of time (comparable to the month-long GPS surveillance at issue in Maynard). The choice will therefore rarely be "should we attach a GPS device or have an officer follow the person around all of the time?" If the former requires a warrant, then the police will be left with one option: develop probable cause and obtain warrant, or leave the person alone. It is therefore the inefficiency of physical surveillance -- and not necessarily the special intrusiveness that GPS tracking entails relative to its physical analogue -- that makes the GPS device such a threat in police hands.