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.
As a result, defense lawyers are challenging the constitutionality of Minnesota's DWI laws. Already, a few district court judges have ruled that Minnesota's DWI laws are unconstitutional in routine DWI cases. Ultimately, the issue will be decided by the Minnesota Supreme Court in the coming months.