The Supreme Court later this month will hear a major genetic-privacy case testing whether authorities may take DNA samples from anybody arrested for serious crimes.

The case has wide-ranging implications, because at least 27 states and the federal government have regulations requiring suspects to give a DNA sample upon some type of arrest, regardless of conviction. In all the states with such laws, DNA saliva samples are cataloged in state and federal crime-fighting databases.

The justices are reviewing a 2012 decision from Maryland's top court, which said it was a breach of the Fourth Amendment right against unreasonable search and seizure to take, without warrants, DNA samples from suspects who have not been convicted.

The upcoming hearing, slated for Feb. 26, has drawn a huge following from civil rights groups, crime victims, federal and state prosecutors and police associations – each arguing their party lines.

The President Barack Obama administration told the justices in a filing (.pdf) that "DNA fingerprinting is a minimal incursion on an arrestee's privacy interests. Those interests are already much diminished in light of an arrestee's status and the various intrusions and restrictions to which he is subject – and that is particularly true of any interest in preventing law enforcement from obtaining his identifying information."

On the other side, the Electronic Privacy Information Center said the indefinite retention of DNA samples raises unforeseen privacy issues. (.pdf)

"As our knowledge of genetics and its capabilities continues to expand, it brings with it new challenges to privacy. Once an individual's DNA sample is in a government database, protecting that information from future exploitation becomes more difficult," the group told the justices in a filing.

DNA testing in the United States was first used to convict a suspected Florida rapist in 1987, and has been a routine tool to solve old or so-called cold cases. It has also exonerated convicts, even those on death row.

At issue before the justices is a Maryland Court of Appeals ruling that arrestees have a "weighty and reasonable expectation of privacy against warrantless, suspicionless searches" and that expectation is not outweighed by the state's "purported interest in assuring proper identification" of a suspect.

The case involves Alonzo King, who was arrested in 2009 on assault charges. A DNA sample he provided linked him to an unsolved 2003 rape case, and he was later convicted of the sex crime. But the Maryland Court of Appeals reversed, saying his Fourth Amendment rights were breached.

Maryland prosecutors argued that mouth swabs were no more intrusive than fingerprinting, but the state's high court said that it "could not turn a blind eye" to what it called a "vast genetic treasure map" that exists in the DNA samples retained by the state.

The Maryland court was noting that DNA sampling is much different from compulsory fingerprinting. A fingerprint, for example, reveals nothing more than a person's identity. But much more 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 issue before the justices does not contest the long-held practice of taking DNA samples from convicts. The courts have already upheld DNA sampling of convicted felons, based on the theory that those who are convicted of crimes have fewer privacy rights.

Maryland's law, requiring DNA samples for those arrested for burglary and crimes of violence, is not nearly as harsh as California's, among the nation's strictest requiring samples for any felony arrest.

The outcome of the hearing is likely already decided, however. Chief Justice John Roberts in July stayed the Maryland decision. In the process, he said there was a "fair prospect" (.pdf) the Supreme Court would reverse the decision.

The high court has previously ruled that when conducting intrusions of the body during an investigation, the police need so-called "exigent circumstances" or a warrant. For example, the fact that alcohol evaporates in the body is an exigent circumstance that provides authorities the right to draw blood from a suspected drunken driver without a warrant.

That said, the justices last month heard arguments on that "exigent circumstances" concept in another closely watched case from Missouri concerning genetic privacy. That case tests whether the police should obtain a warrant to draw blood against the will of suspected drunken drivers.

A decision in that case is pending.