WASHINGTON (AP) — The Supreme Court on Tuesday struggled with what one of the justices called its most important criminal procedure case in decades, whether to let police take DNA from those arrested, but not convicted, in hopes of using it to solve old cases.

Justices seemed conflicted over whether police have a right to take genetic information from people who have only been arrested but not yet convicted of a crime without getting a judge’s approval first, or if the government’s interest in solving cold cases trumped the immediate privacy rights of those under police suspicion of other crimes.