A bill currently being considered in the Colorado Legislature would set limits on how much THC--the psychoactive ingredient in marijuana--drivers in the state can legally have in their blood.

House Bill 1261 (embedded below) is being sponsored by Representatives Claire Levy, a Democrat, and Mark Waller, a Republican. The bill "would allow a person who drives with a tetrahydrocannabinols (THC) blood content of 5 nanograms or more to be charged with DUI."

Levy told the Colorado Independent that the bill is intended to strengthen and specify laws already on the books that prohibit driving while on the influence of drugs.

"There is already a bill that says you cannot drive under the influence of any drug to the extent it impairs your ability to drive," Levy told the Independent. "This is just quantifying the amount of THC you can have in your blood system.. Right now we have, in effect, a zero tolerance policy."

HB 1261, however, is staunchly opposed by the Cannabis Therapy Institute, a medical marijuana advocacy organization, which accused Waller and Levy this week of trying to "curb an imaginary crisis of "stoned drivers" in Colorado.

"Research shows that there is no correlation between THC blood levels and impairment," the Cannabis Therapy Institute said in a release. "The National Highway Traffic Safety Administration released a study in 2004 which shows that chronic cannabis users, such as medical marijuana patients, normally average a much higher concentration of THC in their bloodstream than 5 ng/mL casual users AND that this does not necessarily cause impairment."

The bill is currently being considered by the House Judiciary Committee.

READ THE BILL: