From Westways Magazine (Oct 2016)
We have a genuine traffic-safety concern related to the legalization of recreation marijuana use, including marijuana candies, foods, and concentrates. It has taken generations to educate the driving public about drinking and driving and to strengthen laws to reduce drunk driving. Proposition 64 would create new traffic- safety issues and increase the problem of impaired driving.
Recent Research by the AAA Foundation for Traffic Safety found that fatal crashes involving drivers who recently used marijuana more than doubled in Washington after the state legalized marijuana. In fact, marijuana decreases driver performance and attention, and increases reaction time and lane deviation. The AAA Foundation for Traffic Safety also found that, unlike tests that have been developed over decades to measure blood alcohol content (BAC) to enforce drunk-driving laws, there is no similar, reliable, or scientific way to test for marijuana impairment. That poses a serious challenge for law enforcement to identify and prosecute marijuana-impaired drivers.
The Auto Club believes that Proposition 64 puts traffic safety at risk. It will likely increase the availability and use of marijuana, which will lead to increased drugged driving. You can stop this by voting no on Proposition 64 on November 8.
You can read more from the AAA