US Supreme Court Requires Warrant Before Taking of Blood in DWI Missouri v McNeely 133 S. Ct. 1552 (2013).

Respondent McNeely was stopped by a Missouri police officer for speeding and crossing the centerline. After declining to take a breath test to measure his blood alcohol concentration (BAC), he was arrested and taken to a nearby hospital for blood testing. The officer never attempted to secure a search warrant. McNeely refused to consent to the blood test, but the officer directed a lab technician to take a sample. McNeely’s BAC tested well above the legal limit, and he was charged with driving while intoxicated (DWI). He moved to suppress the blood test result, arguing that taking his blood without a warrant violated his Fourth Amendment rights. The trial court agreed, concluding that the exigency exception to the warrant requirement did not apply because, apart from the fact that McNeely’s blood alcohol was dissipating, no circumstances suggested that the officer faced an emergency. The State Supreme Court affirmed, relying onSchmerber v. California, 384 U. S. 757, in which this Court upheld a DWI suspect’s warrantless blood test where the officer “might reasonably have believed that he was confronted with an emergency, in which the delay necessary to obtain a warrant, under the circumstances, threatened ‘the destruction of evidence,’ ” id., at 770. This case, the state court found, involved a routine DWI investigation where no factors other than the natural dissipation of blood alcohol suggested that there was an emergency, and, thus, the nonconsensual warrantless test violated McNeely’s right to be free from unreasonable searches of his person.