DENVER - A recent ruling by the U.S. Supreme Court could change Colorado's latest debate over marijuana driving limits.
Opponents are hoping lawmakers reject the blood standard again this year, based in part on a ruling issued this week that says officers must try to obtain a search warrant from a judge before ordering blood tests to determine driver impairment.
The high court's decision stemmed from a Missouri drunk-driving case in which a man's blood was taken without a warrant. The prevailing justices determined the blood test was an unreasonable search of an unwilling driver. Justices noted "physical intrusion beneath (the defendant's) skin and into his veins to obtain a blood sample."
Because there's no breath test for marijuana impairment, pot activists hope the ruling inspires Colorado lawmakers to abandon the idea of a pot analogy for drunk-driving standards.
A bill up for a hearing Monday in the state Senate is the fourth attempt by lawmakers to set a blood standard for determining whether a driver is stoned.
"I don't see a feasible way for this move forward, the way it's written," said Jason Warf, head of the Colorado Springs Medical Cannabis Council and an outspoken opponent of the proposed blood limit, set a 5 nanograms per milliliter of blood for THC, the psychoactive ingredient in pot.
Supporters of the bill insist they'll press on. The sponsor of the bill, Republican Sen. Steve King of Grand Junction, said Colorado will rely on the state's "implied consent" standard, which means that licensed drivers agree to blood tests. That "implied consent" negates the need for officers to seek warrants to test blood, he argued.
Colorado drivers can decline blood tests and instead give up their licenses for a year.
"You have already given your consent my having a driver's license," King said. "You have already said, I will give you permission to take blood or breath to determine whether I am in fact impaired by alcohol or drugs."
The bill doesn't expressly address the procedure for taking blood from suspected drugged drivers.
Instead, it states that in criminal driving impairment cases, drivers who test about the 5 nanogram limit can be inferred to be impaired. It's a standard that would allow defendants to argue they were sober, despite elevated THC blood levels. In alcohol DUI cases, defendants above legal blood-alcohol limits can't argue they were safe to drive.
Lawmakers have considered similar driving-high blood standards three times before. But earlier proposals have faltered amid fears that because the body processes marijuana differently than it processes alcohol, a DUI blood analogy is problematic. Current drugged-driving convictions rely heavily on officer observation that a driver isn't sober.
"Marijuana does not metabolize in the same way that alcohol does. Which is part of the reason the Legislature has had so much trouble trying to figure this out," said Sam Kamin, a University of Denver law professor who served on a state panel to craft marijuana regulations.
Opponents of a blood standard are hoping to appeal to senators Monday to accommodate the physical differences between booze and pot.
Sean McAllister, a Denver defense attorney who specialized in impaired-driving cases, said he's hoping lawmakers exempt medical marijuana patients from the bill.
"I think there is an ethical difference between a patient taking a medicine and having certain blood levels, and a person taking it recreationally to get high," McAllister said.