U.S. Supreme Court restricts state laws requiring blood tests in DUI cases.

The U. S. Supreme Court has recently ruled that police officers may not compel the operator of a motor vehicle who is suspected of driving under the influence (DUI) of alcohol or drugs to take a blood test. Breathalyzer tests may still be demanded; and an operator refusing a breathalyzer will still be charged with Refusal. But no longer will an operator be automatically guilty of Refusal for not consenting to a blood test unless a valid search warrant is obtained. In the 7-1 decision, the justices drew a distinction between a breathalyzer test, which requires only blowing into a tube and does not record the driver's DNA, and a blood test which involves the more invasive piercing of the skin and does create a record of the driver's DNA. The more intrusive blood test violates the Fourth Amendment right against "unreasonable search".

The impact of this decision has yet to be determined. Law enforcement officials can typically obtain a search warrant under circumstances in which there is a reasonable suspicion that a crime was committed. But whether local and state police departments will automatically seek search warrants to compel blood tests in cases in which the driver passed a breathalyzer test but is obviously impaired remains to be seen. For now, a person who passes a breathalyzer test but who is under the influence of a drug other than alcohol, may have a better chance of escaping criminal prosecution unless police departments establish new protocols to obtain search warrants for blood tests in DUI stops.