Missouri v. McNeely is scheduled for argument before the Supreme Court tomorrow. The case involves a Missouri man who had his blood drawn during a DWI arrest without giving consent. Missouri is one of 21 states that allows for blood tests without a warrant in drunk driving cases.

The DWI law went into effect on August 28, 2010. Patrolman Mark Winder arrested Tyler McNeely on October 3, 2010 for DWI. He had read an article in Traffic Safety News by a prosecutor who suggest that no warrant was needed for a blood draw of a non-consenting DWI suspect. Relying on this, Winder took McNeely to a local hospital to have his blood drawn without first obtaining a warrant.

McNeely argues that a warrantless blood draw is a violation of one’s Fourth Amendment rights to be free of search and seizure. Missouri asserts that allowing warrantless blood draws for DWI investigations allows the state to effectively enforce drunk driving laws. Additionally, Missouri states that without an expedient blood test, the alcohol in a person’s blood stream could dissipate and destroy evidence.

According to the Christian Science Monitor, attorney generals from 32 states, the District of Columbia, and the Obama Administration are siding with Missouri, and are urging the Supreme Court to conclude that warrantless blood draws are not in violation of the Fourth Amendment.