Abstract: On July 25, 2011, in United States v. Mitchell, the U.S. Court of Appeals for the Third Circuit held that taking a DNA sample from a pre-trial arrestee did not violate the Fourth Amendment. The court did so by holding that taking DNA profiles serves only to identify arrestees, and thus, like fingerprinting, is an acceptable “booking” practice. Unlike fingerprints, however, DNA profiles contain significant personal information beyond that necessary for mere identification. This Comment argues, therefore, that to determine the reasonableness of this intrusion onto arrestees’ expectations of privacy under the Fourth Amendment, courts must consider both the physical DNA collection and the retention of the sensitive personal information in the DNA profile.