Police sampling of the DNA of individuals arrested in connection with serious crimes may become as routine as fingerprinting and photographing as the result of a major Fourth Amendment ruling by the U.S. Supreme Court last week.

Embracing DNA technology as "one of the most significant scientific advancements of our era," the court ruled, 5-4, in Maryland v. King that taking DNA samples with a mouth swab is a "negligible" intrusion that does not violate the Fourth Amendment’s bar against unreasonable searches. During oral arguments in February, Justice Samuel Alito Jr. said the case was "perhaps the most important criminal procedure case that this court has heard in decades."

Justice Anthony Kennedy, writing for the majority on June 3, said, "When officers make an arrest supported by probable cause to hold for a serious offense and they bring the suspect to the station to be detained in custody, taking and analyzing a cheek swab of the arrestee’s DNA is, like fingerprinting and photographing, a legitimate police booking procedure." Chief Justice John Roberts Jr. and justices Clarence Thomas, Stephen Breyer and Alito joined Kennedy’s opinion.

Justice Antonin Scalia, in an angry dissent that he summarized from the bench, predicted that the scope of the decision will not be limited to arrests of those suspected of serious offenses.

"Make no mistake about it," Scalia warned. "As an entirely predictable consequence of today’s decision, your DNA can be taken and entered into a national DNA database if you are ever arrested, rightly or wrongly, and for whatever reason."

The conservative Scalia displayed his libertarian streak in his dissent — a tendency that often places him on the same side as the court’s liberals in Fourth Amendment cases. "I doubt that the proud men who wrote the charter of our liberties would have been so eager to open their mouths for royal inspection," wrote Scalia, who was joined in dissent by justices Ruth Bader Ginsburg, Sonia Sotomayor and Elena Kagan.

Civil liberties and criminal defense groups also criticized the ruling as an erosion of the presumption of innocence in the criminal justice system. "Any American who thinks they’re safe from the threat of DNA sampling, blood draws, and roadside strip and/or rectal or vaginal searches simply because they’ve ‘done nothing wrong’ needs to wake up to the new reality in which we’re now living," said John Whitehead, president of The Rutherford Institute.Maryland Attorney General Douglas Gansler applauded the decision as "a resounding victory for both law enforcement and civil libertarians. This decision will help us solve cases and take criminals off the street. We were confident all along the court would agree that taking a DNA swab is no more invasive than taking someone’s fingerprints — and that DNA is an important tool in both identifying the guilty and exonerating the wrongly accused."

Alonzo King was arrested on assault charges in Maryland in 2009. As allowed by the Maryland DNA Collection Act, police took a DNA sample from King with a cheek swab. Three months later, his DNA record was entered into a state database that matched him to DNA found at the scene of a 2003 rape.

King was tried and convicted of the rape and was sentenced to life in prison. King sought to suppress the DNA evidence on Fourth Amendment grounds, and the Maryland high court, the Court of Appeals, ruled in his favor, finding that King had a "sufficiently weighty and reasonable expectation of privacy" that was not outweighed by the state’s interest in using the DNA to identify him.

According to briefs filed in the Supreme Court, 28 states and the federal government collect DNA at the arrest stage. Laws governing the procedure — including the law at issue before the court — place varying restrictions on how and when the DNA data can be used in law enforcement. Kennedy’s opinion justified the DNA sampling as a "safe and accurate way" to identify people taken into custody — a goal that the court has recognized as a legitimate reason for searching arrestees.

"A DNA profile is useful to the police because it gives them a form of identification to search the records already in their valid possession," Kennedy wrote. "In this respect the use of DNA for identification is no different than matching an arrestee’s face to a wanted poster of a previously unidentified suspect…or matching the arrestee’s fingerprints to those recovered from a crime scene."

But DNA identification is so superior to those other techniques, Kennedy said, that "to insist on fingerprints as the norm would make little sense to either the forensic expert or a layperson.…A suspect who has changed his facial features to evade photographic identification or even one who has undertaken the more arduous task of altering his fingerprints cannot escape the revealing power of his DNA." In addition, Kennedy said, because taking the sample involves "but a light touch on the inside of the cheek," DNA sampling is much less intrusive than, for example, taking blood samples.Scalia scoffed at Kennedy’s reasoning, using unusually derisive language. Justifying the DNA sampling as a way of identifying suspects "taxes the credulity of the credulous," he said, in part because the sample was not processed until three months after King was arrested and identified.

"Does the court really believe that Maryland did not know whom it was arraigning?" Scalia wrote. "It is safe to say that if the court’s identification theory is not wrong, there is no such thing as error."

Contact Tony Mauro at tmauro@alm.com.