I don't think it's going to happen. Regardless of whether or not a state decriminalizes marijuana, it's still against the law federally. That trumps local law. As much as people like to pontificate about states rights, the Constitution is not a treaty. It's the law of the land and gives the Federal Government the last word in things like this.
Further, there is the issue of intoxication while driving. The scientists I've talked to who are considered expert witnesses on intoxication in Colorado seem to agree that a blood level of 5ng/ml is definitely indicative of presumptively impairment and that 1ng/ml is most likely impaired. You can have a blood level of 1ng from second hand smoke. You can have a residual background level much higher than that if you are a habitual smoker. If smoke habitually, you can abstain for several days and still have blood levels well above 1ng/ml. If you area a habitual smoker and quit and then lose weight a year later, the stored THC in your fat cells gets released and your blood level can rise above a presumptively impaired level. What does this all mean? Probably that half the drivers in Colorado at any given time are impaired. Even if we legalized it here, anyone who uses it would be prohibited from driving, maybe even for days at a time.
I would like our society to have the what level of impairment is too much conversation, though. 1ng/ml might have some perceptible level of impairment so that a driver might lose some reaction time, but is it any more significant than having a bad headache, a fight with the wife, stress from work, etc?
There are no easy answers about marijuana. From its demonization under Anslinger to the present, it's been controversial and saddled with cultural baggage that has not always been about the direct effect the drug has on users and society. I believe our current policy of incarceration for drug crimes is misguided at best. The idea that we are populating our prisons at great cost both directly (prisons are pricey) and indirectly (cons don't get jobs easily and it can be an incredibly negative experience to one's life path to go to prison leading to negative social outcomes) with people who are not an inherent danger to society shows a pretty strong dysfunction. I just finished reading Prisons of Poverty by Waquant, and it's a pretty strong indictment of the prison system as a method of class control where drug prohibition is an essential tool of the supporters of the neo-liberal theories of law and order. I think it should be read by everyone who feels seduced by the law and order arguments. Anyway, I digress. Marijuana is complicated, even if you don't smoke it!
