Fifteen years ago, Louisiana adopted a law mandating that “[a] person who is arrested for a felony sex offense or other specified offense . . . shall have a DNA sample drawn or taken at the same time he is fingerprinted pursuant to the booking procedure.” As of mid-2012, 28 states and the federal government had laws providing for DNA sampling before any conviction is obtained. Most other countries with DNA databases also collect samples on arrest.
These laws have provoked conflicting constitutional opinions. The Supreme Court heard argument in Maryland v. King in February 2013 and is likely to rule on the issue in June 2013. For a scoreboard on the litigation and a list of scholarly commentary to date, see http://for-sci-law-now.blogspot.com/2013/03/the-constitutionality-of-dna-collection.html.