Colorado and Washington State recently legalized recreational pot and Massachusetts became the 18th state to OK medical marijuana, but there's no consensus on how soon someone can safely or legally drive after toking up. Studies have reached different conclusions, while states have various drugged-driving standards. King, a Republican lawmaker and local deputy sheriff, wants Colorado to join 14 states that define D-W-High as driving when your blood contains a specific amount of tetrahydrocannabinol. Known as THC, tetrahydrocannabinol is the active ingredient in pot. But the National Organization for Reform of Marijuana Laws, a pro-legalization group, claims there's no scientific consensus on what blood-THC levels impair drivers. "We need to understand that the pharmacokinetics of cannabis are very different from alcohol," NORML's Paul Armentano says. For instance, Armentano says that while alcohol enters the bloodstream slowly through the digestive tract, THC immediately hits a pot smoker's arteries via the lungs. That means users can have hefty blood-THC levels even before marijuana takes effect, but lower amounts even when people are still high, he says. As such, NORML argues that states should use only blood tests in conjunction with other drugged-driving evidence.
Lenny Frieling, a Boulder defense lawyer who heads NORML's Colorado chapter, believes courts should look mostly at such things as how suspects perform in roadside impairment tests. "Blood tests are just one piece of the puzzle," he says.
Arizona, Delaware, Georgia, Illinois, Indiana, Iowa, Michigan, Rhode Island, Utah and Wisconsin make it illegal to drive when your blood contains THC. These states can generally convict you of driving under the influence of pot if tests show anything over zero nanograms of THC or THC metabolites per milliliter of blood. States that allow tiny amounts of pot in your bloodstream
Nevada, Ohio, Pennsylvania and Washington say it's illegal to drive with more than a small amount of THC in your blood. Pennsylvania has a limit of one nanogram of THC per milliliter of blood, while Nevada and Ohio ban anything over two nanograms of THC or slightly higher amounts of metabolites. Washington State has a five-nanogram THC limit, the same standard King wants Colorado to adopt. States that don't rely on blood tests
The remaining 36 states all ban driving under the influence of marijuana, but typically only loosely define what that means.
For instance, Colorado bases convictions on such factors as how you were driving before the police stopped you and whether you failed roadside tests. Playing it safe
In the absence of agreed-to standards, NORML's Armentano recommends pot smokers minimize safety and arrest risks by waiting at least three hours before driving. That's based on conclusions the National Highway Transportation Safety Administration cites on its own website. That said, Armentano says impairment times can vary based on several factors, "so a three-hour window doesn't necessarily apply to everyone." He adds that smoking even a little pot will probably put you over the limit temporarily in states that use THC blood tests. King -- who's been a policeman for 30 years -- can't suggest how long users wait to drive, given that pot potency varies. Instead, he recommends tokers take their cue from drinkers and pick designated drivers before firing up. "You can smoke dope and get a ride, you can smoke dope and walk home or you can smoke dope and call a cab," King says. "Just don't smoke dope and drive."