September 6, 2009 – San Diego DUI lawyer Lawrence Taylor claims that California DUI laws should not be applied to marijuana usage. Unlike alcohol and many drugs, he says, marijuana probably does not impair driving.
On the one hand, the California Department of Justice has found that marijuana impairs psychomotor abilities that are functionally related to driving, particularly at high-dose levels or among inexperienced users. (”Marijuana and Alcohol: A Driver Performance Study,” California Office of Traffic Safety Project No. 087902)
However, the San Diego DUI defense attorney points out, two federal studies contradict this.
In one, the U.S. Department of Transportation conducted DUI research with a fully interactive simulator on the effects of alcohol and marijuana, alone and in combination, on driver-controlled behavior and performance. Although alcohol was found consistently and significantly to cause impairment, marijuana had only an occasional effect.
Accidents and speeding tickets reliably increased with alcohol, but no marijuana or combined alcohol-marijuana influence was noted. (”The Effects of Alcohol on Driver-Controlled Behavior in a Driving Simulator, Phase I”(DOT-HS-806-414).)
Taylor, who heads a large firm of DUI attorneys with offices in Los Angeles, San Diego, Orange County, Riverside and San Francisco, points to another more recent report. Entitled “Marijuana and Actual Performance” (DOT-HS-808-078), it also found that “THC is not a profoundly impairing drug….It apparently affects controlled information processing in a variety of laboratory tests, but not to the extent which is beyond the individual’s ability to control when he is motivated and permitted to do so in driving.”
The researchers found that it “appears not possible to conclude anything about a driver’s impairment on the basis of his/her plasma concentrations of THC and THC-COOH determined in a single sample.” Source.