Eight of the nine justices on the United States Supreme Court agreed with Missouri courts and the criminal defense this month on the application of the warrant requirement in routine drunk driving investigations. The nation’s highest court ruled last week that the warrant requirement of the constitution has application investigations of alleged driving while intoxicated offenses.

The case originated in Cape Girardeau County. A Missouri State Highway Patrol trooper pulled over a car for alleged traffic offenses. The trooper expanded the scope of the investigation to look for evidence of drunk driving. Ultimately, the Missouri driver was charged with DWI. The driver was taken to a hospital for a blood test.

The trial court threw out the blood test results and the Missouri Supreme Court agreed that the warrantless blood draw violated constitutional protections against unreasonable search and seizures. The issue had previous been considered in the U.S. Supreme Court in the 1960s-but the case previously before the court had involved a driver who had been in an accident. Since that time, courts across the nation have come to different conclusions about the scope of the holding in the 1966 high court ruling. Prosecutors appealed the Missouri court decision to the U.S. Supreme Court for its ruling.

The U.S. Supreme Court recognized that blood dissipates naturally in the body over a period of time. But the court says that the natural dissipation of blood is not sufficient by itself to throw out constitutional protections in every DWI investigation. The opinion of the court does not specify when law enforcement may seek a blood test without a warrant (although the 1966 ruling was not overturned). But the court ruled that law enforcement generally must obtain a warrant to lawfully obtain a blood sample in DWI cases.

The important ruling shows that constitutional protections remain important. Many people assume that a person is guilty of an offense when a story of an arrest in printed in the media. But our system of justice is based upon important rules and constitutional protections that are in place to maintain the integrity of the justice system.

Source: News Tribune, “Supreme Court rejects routine no-warrant DUI blood tests,” April 18, 2013