In April the United States Supreme Court handed down a 5-4 decision holding: In drunk-driving investigations, 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.
This case resulted in four separate opinions. The concurring and dissenting opinions focused on the loss of evidence due to the alcohol in the bloodstream being absorbed in the time that it takes a warrant. However, concurring and dissenting opinions provide guidelines and not law.
This holding doesn’t set forth any standards. Every case will be judged by its own facts and a warrant blood draw could be cause for dismissal depending on those facts. The majority opinion written by Judge Sotomayor stressed that getting a warrant should be the default protocol in drunk-driving cases where officers decide to have a blood test made.
What this means for current DWI cases across the country depends on whether it was a breathalyzer or a blood test. Defense attorneys may challenge the validity of and blood test obtained without a warrant. As there are no concrete rules to when a warrant is or is not required, this could result in quite a few trials on DWI cases.