A Missouri police officer stopped a motorist for speeding and crossing the centerline. Suspecting the motorist had been driving under the influence, and after the motorist declined to take a breath test to measure his blood alcohol concentration (BAC), the officer arrested the motorist and transported him to a nearby hospital for blood testing. Althought the motorist refused to consent for the blood test, the officer directed a lab technician to take a sample. The officer never attempted to secure a search warrant. The state argued there would not be enought time to obtain a search warrant because blood alcohol disappates over time. The blood test results indicated that the motorist’s BAC tested well above the legal limit. The officer charged the motorist with driving while intoxicated (DWI).
At the trial court, the motorist 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 motorist’s blood alcohol was dissipating, no circumstances suggested that the officer faced an emergency.
On appeal, the Missouri State Supreme Court agreed with the trial court, and held that a routine DUI investigation where no factors other than the natural dissipation of blood alcohol suggested that there was an emergency, and, thus, the nonconsentual warrantless test violated the motorist’s right to be free from unreasonable searches of his person. The Missouri State Supreme Court relied on Schmerber v. California in which the U.S. Supreme Court held that 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’.
Missouri again appealed the matter to the U.S. Suppreme court, who, in Missouri v. MCNeely, stated that they agreed with the Missouri State Courts.