Koon said it had been at least six hours since he "used his medicine," and the blood test registered 10 nanograms per milliliter of the active ingredient in marijuana, THC. The 86th District Court in Grand Traverse County, MI – the county where Koon was caught – ruled that it took five times that amount to declare a person stoned.
But that was the ruling of a single court. The problem for the Michigan Supreme Court justices was that the state of Michigan hasn't explicitly identified the threshold for being under the influence marijuana, the same way it usually takes a blood-alcohol level of at least .08 to be considered under the influence of alcohol, and charged with driving while intoxicated. The vagaries pitted the state's Zero Tolerance policy against the protections accorded by Michigan's Medical Marijuana Act, and the Zero Tolerance policy lost. We imagine there'll be a rematch – yet another one – soon enough.