KANSAS CITY, Mo. (AP) – The Missouri Supreme Court has thrown out the results of a blood test on an unwilling suspect in a routine drunken-driving stop, ruling the officer should have obtained a judge’s warrant for the test.

In a 2010 case from Cape Girardeau County, the court ruled Tuesday the warrantless test on the unwilling driver amounted to an unconstitutional search. The court said the simple fact that alcohol in blood dissipates over time doesn’t justify the failure to get a warrant.

The Supreme Court said there must be special circumstances to order a warrantless blood test – such as the officer’s involvement in a lengthy accident-scene investigation.

Cape Girardeau County assistant prosecutor Jack Koester says he plans to appeal to the U.S. Supreme Court.