A Better Way to Fight Crime

The brilliance of DNA swabbing


In June 2006, a minor brawl erupted at Ye Olde Six Bells pub in Horley, England. In the aftermath, police arrested Mark Dixie, a chef at the pub, who surprised them by breaking into tears.

He had good reason. As a standard practice in arrests, a DNA swab was taken from him. What the authorities didn't suspect, but he did, is that his DNA would match that of the man who raped and murdered an 18-year-old woman nine months earlier. He was eventually sentenced to life in prison.

This is just one of many cases that have vindicated the use of DNA in cracking crimes. Britain, which now has the world's biggest collection of such profiles, has found it abundantly useful as a law enforcement tool. In a typical month, police get 3,500 matches between samples recovered at crime scenes and DNA profiles in the database.

Now the U.S. government is set to expand its own database to include anyone arrested by federal agents, as well as many foreigners who are detained for one reason or another. It will add more than 1 million samples each year, greatly increasing the chances of getting "cold hits" from crime scenes.

But the expansion alarms some civil liberties advocates, who think it is dangerous to include people who may be innocent. They would prefer to see the files limited to those who have already been convicted of crimes. By that logic, we would throw out the fingerprints of anyone who is arrested but never prosecuted. In reality, we don't. Why? Not because we impute guilt to anyone who is arrested, but because a bigger database is more helpful in solving crimes than a smaller one. And because the only people who stand to be implicated by such information are those who are guilty of later crimes.

We could "protect" innocent arrestees by discarding such helpful identifying information. But we have reached the conclusion that the potential value of preserving it outweighs any burden it places on those who were wrongly arrested.

In some instances, the database can be a boon to the innocent. In 2004, when Chester Turner was implicated in a string of Los Angeles murders through DNA analysis, a man wrongly convicted for three of them was freed from prison.

Opponents of the new system fear that information from the federal bank may someday be used for purposes other than law enforcement—say, screening insurance applicants for certain diseases. But this is a weak excuse for rejecting the administration's proposal.

In the first place, the potential uses of the DNA information kept in databases have been greatly exaggerated. "The profile's not useful for anything much other than identification," says David Kaye, a law and life sciences professor at Arizona State University. "The 'medical' information is, and is likely to remain, no more significant than, say, a blood type."

The actual DNA swabs tell far more. But those are not what goes into the database. The privacy concern is an argument for getting rid of the original samples—not for getting rid of the identifying markers they yield.
Besides, the obvious way to address potential abuses of useful information is by enforcing appropriate rules.

The government might do something alarming with the existing fingerprint files—such as require employers to cross-check prints from all private-sector job applicants. But you don't need to throw out the fingerprints of anyone not convicted to prevent such misuse, as we have found. You can prevent it by not allowing it.

In the case of the DNA database, the looming imposition on the guiltless is minimal. Under the proposed policy, when someone is arrested or detained, his DNA will be taken and a profile included in the federal collection. If he is not convicted, though, that profile will be expunged on his request.

The American Civil Liberties Union thinks the removal should occur automatically. But if keeping the profile is of no concern to the innocent person in question, it's hard to see why it should be of concern to the rest of us. Those who consider it an intolerable invasion of privacy, after all, will avoid it. Those who couldn't care less won't.

DNA analysis is one of the most valuable instruments ever devised for snaring the guilty and exonerating the innocent. This expansion will make it even more potent.