U.S. Supreme Court
Motor Vehicles – OWI — warrantless searches
A warrantless nonconsensual blood draw of a drunk driving suspect violates the Fourth Amendment.
The State nonetheless seeks a per se rule, contending that exigent circumstances necessarily exist when an officer has probable cause to believe a person has been driving under the influence of alcohol because BAC evidence is inherently evanescent. Though a person’s blood alcohol level declines until the alcohol is eliminated, it does not follow that the Court should depart from careful case-by-case assessment of exigency. When officers in drunk-driving investigations can reasonably obtain a warrant before having a blood sample drawn without significantly undermining the efficacy of the search, the Fourth Amendment mandates that they do so. See McDonald v. United States, 335 U. S. 451. Circumstances may make obtaining a warrant impractical such that the alcohol’s dissipation will support an exigency, but that is a reason to decide each case on its facts, as in Schmerber, not to accept the “considerable overgeneralization” that a per se rule would reflect, Richards v. Wisconsin, 520 U. S. 385. Blood testing is different in critical respects from other destruction-of-evidence cases. Unlike a situation where, e.g., a suspect has control over easily disposable evidence, see Cupp v. Murphy, 412 U. S. 291, BAC evidence naturally dissipates in a gradual and relatively predictable manner. Moreover, because an officer must typically take a DWI suspect to a medical facility and obtain a trained medical professional’s assistance before having a blood test conducted, some delay between the time of the arrest or accident and time of the test is inevitable regardless of whether a warrant is obtained. The State’s rule also fails to account for advances in the 47 years since Schmerber was decided that allow for the more expeditious processing of warrant applications, particularly in contexts like drunk-driving investigations where the evidence supporting probable cause is simple. The natural dissipation of alcohol in the blood may support an exigency finding in a specific case, as it did in Schmerber, but it does not do so categorically. Pp. 8–13.
358 S.W.3d 65, affirmed.
Sotomayor, J.; Kennedy, J., concurring in part; Roberts, C.J., concurring in part and dissenting in part; Thomas, J., dissenting.