The Times reports this morning that a man who spent 28 years in prison for a rape and murder he did not commit has been exonerated based on DNA evidence. Sent to jail as a young man — he was 30 — he is now 58, his life an irreversible tragedy. It seems that hardly a week can go by these days without a similar story. Indeed, it was less than a week ago that the Times indeed carried one. This time, an innocent man rotted in jail for only four years.

DNA is a far more powerful forensic tool than are fingerprints, which have been used in criminal investigations since the late 19th century. A criminal with a grain of sense (fortunately, most criminals don’t have one) just needs to wear gloves to avoid leaving fingerprints; but DNA, which can now be successfully found in incredibly small quantities, is much harder to avoid leaving behind. A hair shed, a soda bottle drunk from, will do it.

With its power to establish innocence as well as guilt, one would think that everyone would welcome the emergence of this extraordinary technology. But not the ACLU, which regards the taking of DNA from anyone not convicted of a crime as a gross violation of civil rights. As the ACLU wrote in 2007,

State and Federal DNA databanks are expanding at an alarming rate. A crime prevention tool that was originally intended only to track the most dangerous convicted felons, police departments and other law enforcement agencies across the country have begun collecting and permanently storing DNA from arrestees and other innocent persons. This trend not only represents a grave threat to privacy and the 4th Amendment, but it also turns the legal notion that a person is “innocent until proven guilty” on its head.

How, exactly, does it do that? Fingerprints have been routinely taken from all people arrested for a century and more. Anyone who joins the military, a police department, and many other organizations has his fingerprints taken. Anyone who, at least in New York State, applies for a liquor license has his prints taken. They’re all stored in interlocked databases. What’s different about DNA?

I suppose in some Hitlerian regime such databases could be used to determine those with genetic defects so they could be rounded up, but I think that’s a minuscule risk worth taking if the upside is that many people would be spared jail for crimes they did not commit.

The trouble with crusades — racial justice, civil rights, etc. — is that in a democratic country, they eventually morph into fetishes.