Marijuana and Driving
"Drug Test Results and Accident Risks" from Cal NORML Guide to Interpreting Drug Test Results
Fed study: Booze impact greater than pot on driving CNN, June 25, 2015
Traffic fatalities are “near historic lows" in Colorado following legalization there in 2012.
A recent NTHSA survey, the largest of its kind ever conducted, assessed whether marijuana use by drivers is associated with greater risk of crashes. The survey found that marijuana users are more likely to be involved in accidents, but that the increased risk may be due in part because marijuana users are more likely to be in groups at higher risk of crashes. In particular, marijuana users are more likely to be young men – a group already at high risk.
February 26, 2015 - An important new study shows high blood levels of THC can persist days after smoking following heavy use. Levels above 5 ng/ml, the DUI threshold in WA state, were detected as long as 4 days after use. This ought to put the nail in the coffin of proposals to establish mandatory per se THC blood thresholds for DUI. Highway safety researchers would do well to retarget their efforts towards developing better impairment tests, rather than pursue chemical testing for DUI.
U.S.: No evidence marijuana leads to higher crash risk February 2015
A 20-month survey of drivers in 2013 and 2014 found that drinking and driving dramatically raises the chance of a crash, but didn't find evidence that marijuana use is statistically significant in raising crash rates. See the NHTSA study online
December 19, 2014 - For the third consecutive year, Cal NORML was able to derail an ill-conceived “zero-tolerance” DUI bill that would have criminalized all drivers with detectable traces of THC in their system—a population that includes most daily users. NORML experts provided key expert testimony against the bill, and our e-list subscribers sent over 2,100 messages of opposition to legislators. Numerous accident studies have confirmed that marijuana is not a major risk factor in driving fatalities. In general, however, studies agree that the combination of alcohol and THC is particularly dangerous, if anything worse than "straight" drunken driving.
Marijuana Arrests Steady, DUIs Decline in CA December 12, 2014
Federal Report: Problems with Weed DUI December 08, 2014
NHTSA Official Affirms Little Is Known About Stoned Driving August 4, 2014
Stoned Drivers: The Case Against Panic; Pot prohibitionists undermine their own warnings about legalization and car crashes. Reason August 11, 2014
Accident Stats Show No Evidence of DUI Crisis in California April 29, 2014
More Pot, Safer Roads: Marijuana Legalization Could Bring Unexpected Benefits Forbes, April 3, 2014
The Myth of California's Drugged Driving Epidemic East Bay Express January 13, 2014
Alcohol's role in traffic deaths vastly underreported, study shows Fox News, March 24, 2014
Should Per Se Limits Be Imposed For Cannabis? Humboldt Journal of Social Relations, 2013
THC Concentrations Don’t Predict Driving Impairment High Times, Oct. 2013
VIDEO: Drivers stoned on marijuana test their driving skills (February 2013)
Cannabis and psychomotor performance: A rational review of the evidence and implications for public policy Drug Testing & Analysis (September 2012)
Cal NORML Successfully Opposes Zero-Tolerance DUI Bill in 2012
California posted an impressive 11% decline in fatal auto accidents in 2010. This continues a strong downward trend that started in 2006. Fatalities are down 35% since then. The entire West Coast has experienced similar declines. Colorado also did well, posting a 6.5% in fatal accidents in 2010. As in California, this represents the lowest number of accidents since statistics began in 1994.
Driving, Worker Safety Not Affected by Legalization
July 27, 2010 - A a careful review of the scientific evidence shows that fears about marijuana’s impact on road safety are unwarranted. There is no good scientific evidence that drug testing improves workplace safety.
New Studies Confirm: Marijuana a Lesser Driving Hazard than Alcohol - Drug urine tests unjustified.
Study Shows Marijuana Users are Safer Drivers
Review of accident studies shows marijuana not a major public highway safety hazard, refuting need for "zero-tolerance" DUI laws and bans on public use. Nonetheless, study shows marijuana use is linked to increased injury risk, confirming California NORML's advice to users.
Expert review of drug tests and per se "driving under the influence" limits.