A 5-4 decision Monday in the Supreme Court ruled that police may take DNA samples from arrestees in violent crime cases without a warrant. The ruling, which the Hill noted, "defied the court's traditional ideological divisions," rested on the argument that DNA is identifying information, like fingerprints, and can be collected at the time of arrest. Via the Hill:

Justice Stephen Breyer, a more liberal justice, joined most of the court's conservative bloc in the majority. Justice Antonin Scalia, an ardent conservative, joined three liberals in the dissent...

Scalia's bombastic dissent dismissed the majority's rationale. "I hope that the Maryland officials who read the Court’s opinion do not take it seriously," he wrote.

Scalia said it "taxes the credulity of the credulous" to argue that DNA testing is simply a means of identification. It's a way to gather evidence — and thus Maryland's law doesn't pass constitutional muster, he wrote.

... The case involves Alonzo King, who was arrested in 2009 on charges of first-degree assault. Police took a DNA sample and matched his DNA to an unsolved rape. King was tried and convicted in the rape, but sued to have the DNA evidence suppressed.

He said taking a DNA swab without a warrant violated his Fourth Amendment protections against unreasonable search and seizure.