A Colorado bill that would facilitate the prosecution of drivers operating under the influence of marijuana passed through the House Judiciary Committee Thursday, the Denver Post reports.

The bill passed by one vote and now heads to the House Appropriations Committee. according to the newspaper. The proposed statute would make it illegal to drive with a certain amount of THC in one's blood: 5 nanograms per milliliter.

That amount has been a point of contention, according to the Post, as some lawmakers believe it is too low. Driving under the influence of narcotics is already illegal, but the five-nanogram threshold would aid law enforcement in identifying and convicting offenders.  

The measure has already passed the state Senate, according to the Associated Press.

Medical marijuana advocates have opposed the proposal, saying that it could be detrimental to those who use the drug for its intended purpose. A similar bill failed amid bipartisan opposition last year.

Colorado (one of 16 states, plus Washington, D.C., where medicinal use of marijuana is legal) has become something of a laboratory for legalized marijuana. The Legislature shot down a bill earlier this year that would have set up a banking system for medical marijuana shops, and state residents will vote on a ballot measure later this year that would legalize pot for recreational use.