The sponsor of a doomed bill that would have made it easier to convict people of driving stoned on marijuana said today he will introduce the bill again next year if the medical-marijuana industry doesn’t take a more aggressive stance against toking and driving.

State Sen. Steve King, R-Grand Junction, said he was disappointed that the bill effectively died in the state House Tuesday night. The bill, Senate Bill 117, had received the go-ahead from the state Senate and appeared poised to clear the House when it became entangled in a showdown over civil unions that led to 30 bills dying on the House floor when they weren’t voted on by midnight.

King’s bill would have made it illegal to drive with more than a certain amount of THC — the psychoactive chemical in marijuana — in your system. The limit of 5 nanograms of THC per milliliter of blood that the bill proposed would have been similar to the .08 blood-alcohol standard for drunk driving.

Supporters said the bill was scientifically sound and was needed to send a message that driving stoned is not OK. Opponents said the limit was too low and would have resulted in near-certain convictions of sober drivers.

It is already against the law to drive high, but currently prosecutors must prove impairment on a case-by-case basis. Setting a limit — known as a per se standard — provides a shortcut around that.

King carried a nearly identical bill last year that died in the state Senate. In the interim, the medical-marijuana industry worked with the Colorado Department of Transportation on a public awareness campaign against stoned driving.

But King said that campaign didn’t do enough. The number of blood tests from stoned drivers analyzed by the state toxicology lab continued to increase in 2011 over 2010.

“I’m going to challenge the marijuana industry in our state to step up and do something,” King said.

Last year’s campaign, he said, “absolutely was not enough. It wasn’t even a drop in the bucket.”

In a statement released late Tuesday, the head of the Medical Marijuana Industry Group, a lobbying organization that opposed the bill, said the current law is successful at combating stoned driving.

“We will continue partnering with state agencies, such as the Colorado Department of Transportation, to build awareness about the dangers of drugged driving, and to help make our roads safer,” Mike Elliott, the group’s executive director, wrote in an e-mail.

John Ingold: 303-954-1068 or jingold@denverpost.com