DENVER — A groundbreaking trial funded by Colorado soon will shed light on the use of medical marijuana by veterans suffering from post-traumatic stress disorder.

For the first time, the Drug Enforcement Agency has given the green light to a controlled, clinical trial of medical marijuana for veterans suffering from PTSD.

Local veterans have spent years fighting the Colorado Board of Health and Department of Public Health and Environment to include PTSD as a qualifying condition for medical marijuana, but the board has repeatedly denied the request, citing a lack of scientific evidence.

Now, a $2 million research grant awarded by Colorado has the potential to help provide the evidence many states are seeking.

“It’s very significant,” said Marcel Bonn-Miller, principal investigator for the study.

Bonn-Miller said the trial, which took more than a year to gain approval from the DEA, will be conducted in medical centers in Arizona and Maryland.

“We’re looking at 76 military veterans and examining four different types of cannabis and seeing how it impacts their symptoms,” Bonn-Miller said.

Veterans will smoke marijuana from pipes. A control group will smoke a placebo. The study could take up to three years, but it will still mark an important first for research of this kind.

“Without Colorado’s initiative in setting aside money for this, this work couldn’t get done,” Bonn-Miller said. “The biggest stumbling block or barrier to this research is funding, more so than federal regulations or red tape.”