On April 17, 2013, the U.S. Supreme Court decided Missouri v. McNeely, holding that a nonconsensual, warrantless blood test in a DWI case violated the defendant’s right to be free from an unreasonable search under the Fourth Amendment. The Court ruled that a warrant was required to obtain a sample of the defendant’s blood for alcohol testing. Consequently, the blood test was excluded as evidence in the case.

McNeely is a seminal case in the area of DWI law. Prior to McNeely, the Minnesota Supreme Court ruled that a warrant never is required to obtain a sample of a driver’s blood, breath, or urine in a DWI case because the single-factor exigency of alcohol dissipation creates an exception to the warrant requirement. McNeely, however, rejected single-factor exigency and effectively overruled Minnesota’s prior jurisprudence in this area.