Recreational marijuana use is legal in Colorado and Washington, and officials are still struggling with the issue of how to handle stoned drivers. Just two weeks after marijuana was legalized in Colorado, a driver crashed into a state patrol car, allegedly under the influence of marijuana.
Since marijuana can vary in potency and people metabolize marijuana differently, it is more difficult to set a limit for stoned driving than it is to set a limit for drunk driving. Colorado and Washington have set a limit for five nanograms of tetrahydrocannabinol per millileter of blood, but it is challenging for people to self-assess the amount of THC in their system.
Marijuana impairment can cause dangerous driving, like failing to react to a light change or failing to stay in a lane and maintain a steady speed. Washington statistics indicate that the number of weed-using drivers may be on the rise. About 1,000 drivers tested positive for marijuana in 2012, and 745 tested positive in the first six months of 2013.