wiedzmin writes with an article in Wired about DNA collection from criminals in California. From the article: "A California appeals court is striking down a voter-approved measure requiring every adult arrested on a felony charge to submit a DNA sample. The First District Court of Appeal in San Francisco said Proposition 69 amounted to unconstitutional, warrantless searches of arrestees. More than 1.6 million samples have been taken following the law's 2009 implementation. Only about a half of those arrested in California are convicted."
Note that the State can still appeal the ruling; according to the article, the Attorney General's office has made no comment as to whether they will do so.