Tyler McNeely, who was charged with drunk driving in Missouri, won his case after justices had said that police should have obtained a search warrant before conducting a blood test. McNeely had refused a breathalyzer test, was arrested and sent to a hospital where he refused to take a breath test. As a result, a blood test was ordered over his objections and that is when it was discovered that his blood alcohol concentration was 0.154 percent nearly 30-minutes after his initial refusal.
The high court struck down Missouri's guidelines which they ruled as being too broad citing part of the Fourth Amendment which states that people have rights against unreasonable searches and seizure. The high court has also said state intrusions into one's own body generally require prior review and approval by a judge.
The ruling means that there will not be any warrants issued to obtain blood unless there is probable cause. But law enforcement is asking that they be given flexibility when conducting searches saying that such delays might make blood sample results moot since alcohol concentration will dissipate in the time it takes to get a search warrant. Justice Sotomayor said the "…natural dissipation of alcohol in the bloodstream does not constitute an exigency in every case sufficient to justify conducting a blood test without a warrant". Law enforcement is also asserting a missed opportunity to perform a blood test may mean that justice could be denied. However, it is important to note that the justices say that any warrant requirement can be suspended under difficult circumstances (i.e. if someone's life is in danger or destruction of evidence).