Court: search warrants generally required for DWI blood draws; Warrantless DWI Tests Outlawed

The United States Supreme Court ruled Wednesday that the natural dissipation of alcohol in the human bloodstream is not a sufficient justification by itself to avoid the warrant requirement to conduct a blood draw in a routine drunk driving investigation. The long awaited McNeely decision (we previously previewed the McNeely case and its potential impact on Minnesota DWI cases last month) says that circumstances may arise in individual cases that make obtaining a warrant impractical, but the natural dissipation alone is insufficient to conduct a warrantless blood draw after a driving while impaired arrest.

Minnesota courts previously have ruled that the natural dissipation of alcohol creates a single factor exigency. What that essentially means is that the courts have held that the state did not have to show any other reason to conduct a blood draw without a warrant under Minnesota’s implied consent law if probable cause existed to suspect a driver of drunk driving. The U.S. Supreme Court, however, says no so fast.

The nation’s highest court recognizes that alcohol dissipates in a relatively predictable manner, and some delay may occur as a suspect is transported to a facility where a blood sample can be taken. Generally, criminal defense lawyers know that the dissipation of alcohol varies from person to person, and may involve many different and complex factors. The high court also says that in the 47 years since the U.S. Supreme Court addressed warrantless blood draws in DWI cases in the Schmerber case in 1966, technology has made obtaining a warrant more streamlined.

Justice Sonia Sotomayor says in writing the opinion of a divided court that, “While the desire for a bright-line rule is understandable, the Fourth Amendment will not tolerate adoption of an overly broad categorical approach that would dilute the warrant requirement in a context where significant privacy interests are at stake.” The court says that law enforcement should generally be required to obtain a warrant before obtaining a blood sample in a DWI investigation, but the issue may have exceptions on a case-by-case basis.


He has won jury trial cases in misdemeanor and felony cases and in DWI’s and non-DWI’s. He is a member of the Minnesota Society for Criminal Justice, which only allows the top 50 criminal defense attorneys in the state as members. He is a frequent speaker at CLE’s and is often asked for advice by other defense attorneys across Minnesota.

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