Drunk drivers are not the biggest problem on California's roads according to a new survey from the  California Office of Traffic Safety. Out of 1,300 drivers who were tested in nine cities on Friday and Saturday nights, 14 percent were found to have drugs in their system, while only 7.3 percent were found with alcohol. Marijuana was slightly more prevalent than alcohol, found in 7.4 percent of drivers. The official line from the director of the Office of Traffic Safety is that the "results reinforce our belief that driving after consuming potentially impairing drugs is a serious and growing problem." A press release explains that drugged driving goes less frequently noticed and it's pricey to test for toxicology. But, at least in the case of marijuana, which is now legalized in some states, there have been questions as to just how dangerous driving stoned is. Maia Szalavitz at Time writes that "Research suggests that stoned users on the road are not as impaired as those who drink alcohol are, and there is some evidence that those who use marijuana, particularly for medical purposes, may be staying off the roads anyway."  In summer 2011 the addiction and recovery website the Fix looked at the challenges involved in determining just how much marijuana makes a person impaired. 

Though Szalavitz explained that the drivers who participated were not threatened with legal action, she also points out that the new research "likely under-represents the real rate of potentially performance-impairing drug use by drivers" people who are aware of their state of intoxication probably aren't going to pull over.