Exigency for a Blood Draw in an Impaired Driving Case: Constitutional Parameters and Practical Approaches.

• Author: Smith, Rachel

This article was originally published in the National Traffic Law Center's Between the Lines newsletter in October 2022 under NHTSA cooperative agreement 693JJ91950010. It is reprinted here with the permission of the National Traffic Law Center.

In an impaired driving case, a blood draw and resulting toxicology results can be critical evidence for the State's case. A blood draw is a search like any other Fourth Amendment search. For this reason, it may be taken pursuant to a search warrant based on probable cause the driver was impaired OR one of the accepted exceptions to the search warrant requirement, including exigent circumstances. The United States Supreme Court has held that, "Nothing prevents the police from seeking a warrant for a blood test when there is sufficient time to do so in the particular circumstances or from relying on the exigent circumstances exception to the warrant requirement when there is not." (1)

Schmerber v. California is the starting point for examining exigent circumstances for a blood draw in an impaired driving case. (2) In Schmerber, the driver was believed to be impaired and was arrested at the hospital while receiving treatment for injuries suffered in a crash. The Court held that 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.'" (3) The Court first ascertained that the officer had sufficient probable cause for the impaired driving arrest and then went on to assess the constitutionality of the warrantless search. In the Court's analysis, the fact that alcohol is eliminated from the blood over time, the amount of time it took the accused to reach the hospital and for officers to investigate the offense left law enforcement with "no time to seek a magistrate and secure a warrant." (4)

Compare this to the Missouri v. McNeely case in which a warrantless blood draw from an impaired driver was obtained after a routine impaired driving stop, investigation, and arrest. (5) The state argued that the natural dissipation of alcohol in the blood weighed in favor of finding exigent circumstances in impaired driving cases. However, the Court held that, while natural dissipation of alcohol in the blood may support a finding of exigency in a specific case, as it did in Schmerber, it does not do so categorically. Whether a warrantless blood test of a drunk-driving...