Josh Gerstein over at Politico sent Threat Level his piece underscoring once again President Barack Obama is not the civil-liberties knight in shining armor many were expecting.

Gerstein posts a televised interview of Obama and John Walsh of America’s Most Wanted. The nation’s chief executive extols the virtues of mandatory DNA testing of Americans upon arrest, even absent charges or a conviction. Obama said, “It’s the right thing to do” to “tighten the grip around folks” who commit crime.

When it comes to civil liberties, the Obama administration has come under fire for often mirroring his predecessor’s practices surrounding state secrets, the Patriot Act and domestic spying. There’s also Gitmo, Jay Bybee and John Yoo.

Now there’s DNA sampling. Obama told Walsh he supported the federal government, as well as the 18 states that have varying laws requiring compulsory DNA sampling of individuals upon an arrest for crimes ranging from misdemeanors to felonies. The data is lodged in state and federal databases, and has fostered as many as 200 arrests nationwide, Walsh said.

The American Civil Liberties Union claims DNA sampling is different from mandatory, upon-arrest fingerprinting that has been standard practice in the United States for decades.

A fingerprint, the group says, reveals nothing more than a person’s identity. But much can be learned from a DNA sample, which codes a person’s family ties, some health risks, and, according to some, can predict a propensity for violence.

The ACLU is suing California to block its voter-approved measure requiring saliva sampling of people picked up on felony charges. Authorities in the Golden State are allowed to conduct so-called “familial searching” — when a genetic sample does not directly match another, authorities start investigating people with closely matched DNA in hopes of finding leads to the perpetrator.

Do you wonder whether DNA sampling is legal?

The courts have already upheld DNA sampling of convicted felons, based on the theory that the convicted have fewer privacy rights. The U.S. Supreme Court has held that when conducting intrusions of the body during an investigation, the police need so-called “exigent circumstances” or a warrant. That alcohol evaporates in the blood stream is the exigent circumstance to draw blood from a suspected drunk driver without a warrant.