Reading the U.S. Supreme Court’s 5-4 decision of June 3 in Maryland v. King, which upheld the right of the state to take a DNA swab from a person who was arrested, but not convicted, and use it to tie him to an unsolved rape, left me with two minds. On the one hand, every time any part of the government invades the body of any person, that should be ground for concern. On the other, the procedure took just a couple of seconds, was far less intrusive than a blood sample, was less bothersome (and messy) than fingerprints, and actually caught a dangerous rapist.

Before turning to the legal and policy issues, a few facts relative to the Maryland law, not all of which are applicable to the laws of other states, need to be on the table. The right to take a DNA swab applies only when a person is arrested for a crime of violence, which includes burglary. Under the procedure, the accused opens his mouth, and a swab, like a Q-tip, is touched against his inside check, which picks up the material necessary to do the DNA testing. If the accused is not charged, or he is acquitted, the sample is removed from the files. And while a person’s DNA can reveal many personal details, the sample taken by this method can be used only to determine if the person from whom it was taken is the same as a person whose DNA had been previously obtained, in this instance from the evidence in a rape case.

The constitutional issue in King was whether the state could use the DNA to try to get a match with an unsolved crime before King had been convicted (or had pleaded guilty) to the crimes for which he was arrested. Everyone seems to agree that once a person has been convicted (at least of a crime of violence), a DNA swab could be taken and used for the purposes used here. And if all the state did was take the swab upon arrest, and not use it until the accused was found guilty, there probably would have been no case, even if there had been an unconstitutional search when the swab was done. Thus, in practical terms, the issue is whether a state may take and use a DNA swab to try to solve an unsolved crime during the period from arrest to conviction. The opinions do not indicate what percentage of persons arrested for crimes of violence are found (or plead) guilty, but the persons harmed by Maryland’s practice are only those who are both not guilty of the charge for which they were arrested and are charged with another crime as a result of a DNA match.

Justice Anthony Kennedy writing for a mainly conservative majority, but including the pragmatist Justice Stephen Breyer, does not contest that taking a swab is a "search," subject to the Fourth Amendment if done routinely. Nor does he suggest that the state could simply do one on every person within its borders and use it to establish a data bank to deal with unsolved crimes. He nonetheless sustained this practice on the ground that it was a form of obtaining or confirming the accused’s identification, akin to photographing or fingerprinting a suspect. That justification, not very convincing when read on its own, falls completely apart in the face of Justice Antonin Scalia’s trenchant dissent. As Scalia convincingly shows, the one thing that the DNA evidence does not do is help identify the suspect. Indeed, Maryland law precludes it from being used for that purpose, and the way that it was employed in this case and others shows that it is used solely to solve other crimes. And that, according to Scalia, is precisely what searches may not do, absent probable cause to believe that the evidence is sought for a crime that the person being searched is believed to have committed, a standard that was plainly not met here.

Lurking in Kennedy’s opinion is the largely unstated rationale that what was done here was reasonable and in a good cause—but then convicting guilty people is always a good cause. Moreover, the procedure is hardly intrusive, and indeed is not in the same league with the cavity searches for everyone being held in the county jails that was upheld by the Court in Florence v. Burlington just a year ago. To be sure, the justification there was safety of the guards and other inmates, but I would venture that most people not steeped in the Fourth Amendment would support the inmate’s position in Florence before they would the defendant’s in a DNA swab case.

Kennedy also observes that DNA can result in overturning unjust verdicts by identifying the true perpetrator, an occurrence that happens far too often. In response, Scalia observes that the CODIS database is only for unsolved crimes, not those for which a conviction has already been obtained. If true, that is a defect, but one that can be fixed by keeping in CODIS all DNA evidence from all crimes, most of which are unsolved for at least several weeks or months. And the ability not only to convict a guilty person, but to lock him or her away and prevent further violence, is another significant plus.

Scalia rightly worries about the limits of the majority’s permission to obtain DNA swabs and use them. In Maryland, the police can take a swab only for crimes of violence, but the identification rationale would not seem so limited and might allow DNA swabs for even traffic offenses. And if identification is the rationale, why should the state ever have to destroy the evidence because if the search is valid when done, how does it become unconstitutional if the charges are dropped? Hopefully, state legislatures will refuse to extend the decision to its logical extreme, because sensible policy can always be used to prevent intrusions that might not be unconstitutional.

What then do we do about the Fourth Amendment? Is it so clear, as Scalia asserts, that the only searches that are valid are those for which there is a probable cause or some other justification, such as the safety of the arresting officers and others, or the need to prevent destruction of evidence? The Constitution prohibits only "unreasonable searches and seizures," and perhaps it would be more analytically sound and more convincing to the public, if the Supreme Court simply said, "this DNA swab and its use to catch a rapist" was not an unreasonable search and hence was valid. That approach might cause some doctrinal changes in the law, but it would probably be a more honest way of dealing with this issue.

Alan B. Morrison is the Lerner Family Associate Dean for Public Interest Law at George Washington University Law School, where he also teaches constitutional law.