Marijuana DUI Standard Dies A 3rd Time In CO Associated Press May 15, 2012 Exclusive Web Content, Medical Marijuana News, Politics, The War On Drugs DENVER (AP) — A marijuana blood limit for drivers has been rejected for the third time in Colorado. The state Senate fell a single vote short Tuesday on a bill setting a blood standard for THC, the psychoactive ingredient in marijuana. The vote means the proposal is likely dead for the year. Passage of the bill would have made Colorado the third state with a blood-level limit for marijuana, much as the nation has a blood-alcohol limit of .08. Currently, drugged-driving convictions depend on officer observations. Marijuana activists and some lawmakers from both parties argued that the blood standard is an unfair measure of driver impairment.