How Long Should Marijuana Users Wait Before Driving? It's an Open Question in Pot-Legal Colorado and Washington

marijuana (select to view enlarged photo)

SANTA MONICA, Calif.--January 17, 2013: When Washington and Colorado voted to legalize recreational marijuana use in November, both states' lawmakers were forced to consider whether to update their DUI laws. But according to Edmunds, the solutions aren't exactly cut and dried.

“Marijuana and alcohol affect users very differently, so it doesn't always make sense to simply lump a marijuana DUI with an alcohol DUI”

"Marijuana and alcohol affect users very differently, so it doesn't always make sense to simply lump a marijuana DUI with an alcohol DUI," says Edmunds Features Editor Carroll Lachnit. "Everyone knows that driving under the influence of marijuana is dangerous, but there's never been a national standard in place to identify someone who's 'legally stoned' the way we can identify someone who's 'legally drunk.'"

The state of Washington made the first attempt to set that standard with a new law that makes it illegal to operate a motor vehicle with a blood level of 5 nanograms per milliliter of THC -- the active ingredient in marijuana -- as detected by a blood draw. If a driver exceeds this threshold, he or she will face the same conviction as a driver under the influence of alcohol or other drugs. Colorado is considering a similar law, but as currently proposed it would give latitude for those over the limit to argue that they were not impaired.

According to advocates of marijuana law reform, detected levels of THC in someone's system does not necessarily have a direct relationship to impairment. As a result, there's a debate over how long someone should wait to drive after smoking marijuana. The National Highway Traffic Safety Administration (NHTSA) says that marijuana can impair driving performance for up to three hours after use. But even marijuana advocates admit that number may be too conservative. Edmunds spoke with one attorney in Washington who counsels medical marijuana users to wait at least 10 hours. Another attorney in Colorado says that any marijuana user should get a good night's sleep before getting behind the wheel.

Edmunds has more details on what marijuana users -- especially those in Washington and Colorado -- should know before they decide to get behind the wheel at Marijuana and Driving Laws.

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