EDITOR’S NOTE: This story has been updated to reflect that the hearing originally scheduled for Tuesday on the PTSD medical marijuana bill has been postponed.

Post-traumatic stress disorder would be eligible for medical marijuana treatment in Colorado under a proposal in the legislature.

Advocates believe this is the year to finally add PTSD as a qualifier for medical marijuana, after previous attempts in the legislature and through state agencies failed.

What’s encouraging to proponents is that the bill was introduced favorably after an interim legislative committee studying marijuana issues unanimously referred the measure.

But already a roadblock has been identified.

Senate Republican Leader Chris Holbert of Parker said Monday that lawmakers are waiting on a legal opinion from legislative counsel, which would answer whether the legislature has the authority to determine qualifiers for medical marijuana treatment.

“There’s some discussion with doctors and psychiatrists as to whether there’s a constitutional question here,” Holbert told reporters Monday morning.

The issue revolves around whether the medical marijuana law in the state constitution only allows for the state health department to add qualifying conditions for marijuana, which would tie the legislature’s hands.

Senate Bill 17, which would add PTSD as a condition, was scheduled to be heard in the Senate State, Veterans and Military Affairs Committee Tuesday morning. Staff for Senate Democrats said the hearing was postponed because the legal opinion is not ready. Sponsors of the bill hope to hold a hearing next week.

The bill is sponsored by Sen. Irene Aguilar, D-Denver, and Rep. Jonathan Singer, D-Longmont.

Attempts to convince state health officials to add PTSD as a qualifying condition through rule-making failed in the past, so supporters – led largely by military veterans – hope to convince lawmakers to support it.

If they do, Colorado would join 19 other states and Washington, D.C., in allowing cannabis for PTSD treatment.

Supporters will also have to combat claims by the medical community that there is insufficient medical evidence that marijuana is an effective treatment for PTSD, despite emotional pleas from veterans.

Lawmakers are also tying up loose ends from marijuana legalization as a whole, including prohibiting advertising for marijuana without a valid retail license. That measure received initial approval from the full Senate on Monday. It must receive a final vote in the Senate before moving to the House.

The bill comes after law enforcement reported seeing Craigslist ads for marijuana from growers and distributors not licensed to sell.

“That’s called drug dealing,” said Sen. Bob Gardner, R-Colorado Springs.

Gardner, when he was a state representative in 2013, compared marijuana magazines to pornography in an effort to require stores that allow entry to shoppers under age 21 to place cannabis magazines behind the counter. That effort was deemed unconstitutional.

And lawmakers still need to address Gov. John Hickenlooper’s budget request to fund a crackdown of the so-called “gray market,” in which people use legalization to grow large amounts of marijuana legally at home, but then sell the product illegally on the black market.

The governor has requested around $6 million to assist local law enforcement with efforts to control those “gray” activities.