ST. PAUL — A state law making it a crime for someone arrested on suspicion of drunken driving to refuse a urine test without a warrant is unconstitutional, the Minnesota Court of Appeals said Monday, following an earlier ruling that blood tests without a warrant are unconstitutional in such cases.

While the Minnesota Supreme Court ruled in February that warrantless breath tests of people suspected of drunken driving are constitutional, the Court of Appeals ruled in October that warrantless blood tests are not. Monday’s ruling applied similar legal logic to warrantless urine tests.

The decision reversed the test-refusal conviction of Ryan Mark Thompson, who refused to submit to a blood or urine test when he was stopped for suspected drunken driving in Owatonna in 2012.

The three-judge appeals panel said it acknowledged “that a urine test is less intrusive than a blood draw,” which requires inserting a needle through the person’s skin. But it said a urine test is “far more intrusive than a breath test,” and that a warrantless search of a person’s urine “would invade one of the most private of human activities.”

The U.S. Supreme Court earlier this month agreed to decide whether states can make it a crime for a driver to refuse to take an alcohol test even if police have not obtained a search warrant. It will hear arguments next year involving the Minnesota Supreme Court decision on breath tests.