California law requires police officers to take DNA samples from people who've been arrested, but never convicted, of a crime.
Law enforcement officials gather 11,000 DNA samples a month that are then logged into a state or federal database.
Police can use those samples to solve other crimes when DNA is found at another crime scene, but civil rights advocates say those DNA swabs are an unconstitutional "search and seizure" and is an invasion of privacy.
The two sides will square off today at the 9th Circuit Court of Appeals in San Francisco
Laurie Levenson, former federal prosecutor and a professor at Loyola Law School