The U.S. Supreme Court ruled on Monday that police can take DNA samples from suspects arrested of serious crimes without a warrant.
The high court ruled five to four on the issue.
Five of the justices said DNA testing was a legitimate procedure like fingerprinting.
At least 28 states and the federal government now take DNA swabs after arrests.
Privacy advocates argued that taking a suspect's DNA without a search warrant violates the fourth amendment of the U.S. Constitution.
The four dissenting justices said that the court was allowing a major change in police powers.
"Make no mistake about it: because of today's decision, your DNA can be taken and entered into a national database if you are ever arrested, rightly or wrongly, and for whatever reason," conservative Justice Antonin Scalia said in a sharp dissent which he read aloud in the courtroom.
A court in Maryland had ruled it illegal but monday's ruling reverses that decision.