Too stoned to drive? DUID laws.

• Author: Sullum, Jacob
• Position: Citings - Driving under the influence of a drug

INITIATIVE 502, which legalized marijuana in Washington state, also established a new standard for driving under the influence of a drug (DUID): Any motorist with five or more nanograms of THC per milliliter of blood is now automatically considered too stoned to drive, even if he isn't. Colorado's marijuana legalization initiative, Amendment 64, did not address the DUID issue, but the state legislature is considering a variation on the five-nanogram standard that also could result in the conviction of motorists who do not actually pose a threat to public safety.

The Colorado General Assembly has rejected a five-nanogram cutoff twice before because of doubts about whether it is a good measure of impairment. Experiments, including tests by TV stations in Seattle and Denver, indicote that many people can drive competently at THC levels far above five nanograms, especially if they are regular consumers who have developed tolerance and become accustomed to marijuana's effects.

But in February, Colorado's House Judiciary Committee unanimously approved a bill that would allow DUID convictions based on nothing more than a five-nanogram reading. Unlike a per se standard, the bill--which was endorsed by the Amendment 64 Implementation Task Force, a panel appointed by Gov. John Hickenlooper to advise the legislature...