DENVER — A marijuana blood limit for drivers was rejected for a fourth time in the Colorado Senate, where bipartisan skepticism on the pot analogy to blood-alcohol limits helped sink the measure on Monday.
The Senate Judiciary Committee voted 4-1 to reject the blood standard after a long hearing that has become something of an annual tradition in the Senate: Reviewing the scientific basis for using marijuana content in blood to determine whether a driver is stoned.
"This is a significant public safety concern," said Matt Durkin, a state assistant attorney general and supporter of the bill, which would have limited drivers to 5 nanograms per milliliter of blood for THC, pot's psychoactive ingredient.
Durkin worried that recreational pot use will spike because of last year's vote to defy federal drug law and declare marijuana OK in small amounts for people over 21. Washington state also voted to legalize pot last year, but voters there included a 5 nanogram driving limit for impairment cases.
Durkin and other members of law enforcement tried unsuccessfully Monday to persuade senators that Colorado's pot vote makes a blood driving limit necessary here, too. Driving while impaired is currently illegal, though cases now rely heavily on officer observation of a driver's behavior, such as drifting out of lane.
Lawmakers who voted against the bill pointed Monday to Colorado's recent vote, too. They wondered whether increased marijuana use could prompt overzealous blood sampling in impaired-driving cases.
Asking about routine police checkpoints, Democratic Sen. Lucia Guzman of Denver asked, "Are they going to get in some kind of trouble just because of how they're smelling?"
Another element cited by senators who rejected the bill was a ruling from the U.S. Supreme Court last week that said police in most cases must get a warrant before taking a blood sample as evidence, if the driver doesn't consent to having blood taken.
The sponsor of the Colorado bill insisted that police here would be able to follow the blood ruling while still enforcing a 5 nanogram marijuana limit. But other lawmakers were skeptical.
"I take it very seriously for people to drive impaired. I also take it very seriously for the government to prosecute people who aren't impaired," said Sen. Kevin Lundberg, R-Berthoud.
The bill's failure underscored the difficulty policymakers nationwide have had addressing drugged driving.
Unlike alcohol, marijuana stays in the blood long after the high wears off, and there is no quick test to determine someone's level of impairment. The White House has asked states to set a blood-level standard upon which to base drugged-driving convictions but has not said what that limit should be.
Colorado lawmakers can't seem to agree, either. The Democratic House has voted more than once to set a 5 nanogram pot driving limit, and Democratic Gov. John Hickenlooper specifically asked lawmakers to pass it last year when he called them into a special session. But senators can't seem to agree to a fair standard.
A senator who has sponsored multiple failed driving-stoned bills, Sen. Steve King, R-Grand Junction, argued Monday that his bill is needed to keep drivers safe from pot-smoking drivers.
"Just because they have the right to have medical marijuana doesn't give them the right to drive under the influence," King said.
But senators again declined to pursue the blood standard, citing scientific uncertainty and a current drugged driving conviction rate that hovers around 90 percent.
"What is the problem we're trying to solve?" asked Sen. Jessie Ulibarri, D-Commerce City and one of the votes against the bill.