After Maryland arrested Alonzo King on assault charges, booking personnel used a cheek swab to collect his DNA. The profile was entered into CODIS and matched evidence from an earlier unsolved rape, leading to King’s prosecution and conviction. The Maryland Court of Appeals held that the collection was an unreasonable search, and the U.S. Supreme Court reversed. The Court held that a cheek swab is a Fourth Amendment search but that collecting DNA from an arrestee charged with a serious offense is reasonable as part of the booking process. The government has a legitimate interest in accurately identifying an arrestee, assessing the risks posed by a person entering custody, and determining whether the person is wanted for another offense. The intrusion is limited because the swab requires only a light touch inside the cheek, and Maryland’s statute required destruction of the sample in specified circumstances, including when the qualifying charge did not result in a conviction. The Court therefore upheld the search without requiring individualized suspicion or a warrant. Justice Scalia dissented, arguing that the practice was designed to solve unrelated crimes rather than identify King. The judgment was reversed.