Michigan's highest court smartly overturned a 2006 ruling that 11-carboxy-THC — a long-lasting byproduct of metabolism created when the body breaks down the psychoactive ingredient of marijuana — is a schedule 1 controlled substance. Previously, people could have been charged with a driving offense involving drugs long after they had ingested or inhaled marijuana because the metabolite remains in the body for a month or more after use. Prosecutors will now have to prove drivers had marijuana or its active ingredient in their systems at the time they are alleged to have been driving while drugged.