Swabbing the inside of a cheek has become part of the custodial arrest process in many jurisdictions. The majority view (thus far) is that routinely collecting DNA before conviction (and analyzing it, recording the results, and comparing them to DNA profiles from crime-scene databases) is consistent with Fourth Amendment protections against unreasonable searches and seizures. However, some judges and commentators have argued that DNA sampling in advance of a determination by a judge or grand jury of probable cause for the arrest or charge is unconstitutional. This essay shows that this demand is largely unfounded. Either warrantless, suspicionless DNA collection before conviction is unconstitutional across the board or it is permissible immediately after the arrest. The middle ground of requiring a probable-cause determination for an unrelated offense turns out to be inhospitable.
David H. Kaye, Drawing Lines: Unrelated Probable Cause as a Prerequisite to Early DNA Collection, 91 N.C. L. Rev. Addendum 1 (2012).