By Sherry F. Colb
In my column for this week, I discuss the case of United States v. Mitchell, which the Third Circuit has set to be argued en banc (before the whole court of appeals). This case takes up the question whether federal law, which currently requires routine DNA sampling of people arrested for specified offenses (even before they have been tried and convicted) violates the Fourth Amendment right against unreasonable searches and seizures. In my column, I consider the arguments made by the district judge (who refused to allow DNA sampling), including the copious data available in a person's DNA and the notion that people ought to be treated as "innocent until proven guilty."
In this post, I want to ask whether the Supreme Court of the United States ought perhaps to reconsider its overall commitment to the idea that people relinquish privacy when they either discard or voluntarily convey materials (containing highly personal information) to third parties.
In the case of California v. Greenwood, the Supreme Court held that people have no reasonable expectation of privacy in the garbage that they leave at the curb for collection. As a result, police may -- without even triggering the protections of the Fourth Amendment -- pick up people's garbage and wade through it to find evidence or any sort of information they might find interesting. This means, for example, that if you or your partner takes a home pregnancy test and throw it in the trash, a police officer can -- without a hint of crime-related suspicion -- retrieve that test and learn that someone in your household is pregnant.
If we imagine that police only go through garbage when they fully expect to find evidence of crime, then we might not worry about the "curious cop" scenario. On the other hand, if the purpose of having the Fourth Amendment "cover" particular police conduct is a fundamental concern about abuse of power, it might be appropriate to demand some showing of suspicion (in the form of probable cause and a warrant, for example) before allowing a police officer to go through your trash, just as the officer must have probable cause to look around inside your home.
To return to DNA collection, it is now not that difficult to collect a DNA sample from people without having to take blood or a buccal swab (the two methods of DNA collection that at least facially implicate the Fourth Amendment right against unreasonable searches, even now). People discard DNA wherever they go. But so long as people are thought to have no reasonable expectation of privacy in the things that they discard or give away, it is difficult to see how existing Fourth Amendment doctrine can stop the FBI or state and local police from investigating individuals' most personal biological profiles from discarded hair or skin cells. Indeed, police could probably obtain DNA from emptying a person's garbage, in which the Court has already said the individual has relinquished any prior expectation of privacy.
There are some cases that point in another direction, however, as I discuss in the column and as I have addressed in my criminal procedure scholarship (including an article in Stanford Law Review entitled "What Is A Search?"). Rather than utilizing these cases to support protecting DNA, however -- as the Third Circuit will seemingly have to do if it wants to affirm the district court -- the most principled way for the Supreme Court to protect such privacy would be to overrule Greenwood and recognize that we do in fact have a reasonable expectation of privacy in the things that we discard, such that mining them for information ought to require individualized suspicion and a warrant. Whether the Court would be willing to take such a step is, of course, another matter.