A federal judge in Pittsburgh says that collecting DNA from a person simply arrested for a crime and not yet convicted is unconstitutional.

In a 20-page opinion issued on Friday, U.S. District Judge David S. Cercone wrote that the idea of comparing DNA collection to fingerprinting -- as government attorneys have done -- is "pure folly."

"Such oversimplification ignores the complex, comprehensive, inherently private information contained in a DNA sample," the judge wrote.

The biological material can reveal predisposition to thousands of genetic conditions, he went on, as well as identify genetic markers for traits like aggression, sexual orientation and criminal tendencies.

The Department of Justice issued a rule that took effect in January requiring that all federal arrestees have their DNA collected and cataloged.

That rule was challenged here in July, when Ruben Mitchell, who faces drug charges, asked the court to block collection.

While a variety of courts have upheld the collection of DNA post-conviction, it is a new issue for arrestees.

There has been one other decision on the issue -- in the Eastern District of California, where a judge ruled that the collection is not an infringement of the Fourth Amendment right to be free from unreasonable search and seizure.

But in his opinion, Judge Cercone fully disagreed with that court, saying that neither the judge nor the government, "addresses the moral polestar of our criminal justice system -- the presumption of innocence."

If law enforcement officers believe the collection of DNA can help solve a past or ongoing crime, nothing stops them from seeking a search warrant and obtaining the material, the judge said.

Attorneys for the U.S. attorney's office argued that Mr. Mitchell already has a diminished expectation of privacy -- his cell is searched and his phone calls are recorded -- because he is being held in jail pending trial.

But Judge Cercone did not agree that that allows for DNA collection.

"Though pretrial detainees have a diminished expectation of privacy as it relates to legitimate penological interests, the Fourth Amendment does not stop at the jailhouse door," he wrote.

As for the government's argument that DNA collection is another tool for identification, the judge said it is more than that.

"[It] represents a quantum leap that is entirely unnecessary for identification purposes," he wrote. "The only reasonable use of DNA is investigative, it is not an identification science it is an information science. The identification issue in this instance is a red herring, as there is no compelling reason to require a DNA sample in order to 'identify' an arrestee."

Bruce Ledewitz, who teaches both constitutional and criminal law at Duquesne University, said there is no precedential value to Judge Cercone's decision.

While other district court judges here will consider Judge Cercone's opinion, they are not bound to follow it, he said.

The Supreme Court could ultimately take on this issue, but Mr. Ledewitz said that wouldn't likely happen until after there is a split among Circuit Courts.

He suspects that the federal government will continue taking DNA from arrestees unless and until there is a civil, class-action suit filed to stop the practice. Until then, Judge Cercone's decision applies only to Mr. Mitchell and no other defendants.

U.S. Attorney Mary Beth Buchanan declined to comment on the opinion.

"We're consulting with the Department of Justice to determine the appropriate course of action."

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