Montana report shows more DUI samples testing positive for marijuana

Montana State Crime Lab
Posted at 9:30 PM, Aug 09, 2022

HELENA — A report from the Montana Department of Justice shows the number of DUI cases where a sample has tested positive for marijuana-related substances has increased over the last few years – but it’s an issue that’s more complex than just a single number.

The information comes in the 2021 annual report from the DOJ’s Forensic Science Division – commonly known as the state crime lab.

In 2021, the first year after voter-approved Initiative 190 decriminalized possession of marijuana, the crime lab reported 621 DUI cases where samples tested positive for THC – the compound that gives marijuana its high – or the products it breaks down into. The report noted that is a 17% increase over 2020, when there were 530 such cases.

However, it’s not a trend that only began then. In 2019, there were 464 DUI cases testing positive for marijuana-related substances. There were 454 in 2018 and 284 in 2017.

MHP Sgt. Jay Nelson says that data matches with what troopers have seen on the roads. He said the agency can’t point to one factor to explain the entire increase.

“I think it’s a combination of all this,” Nelson said when asked if other states expanding access to marijuana played a role. “To say specifically it’s about legalization, I don’t think we have the data to show that.”

Last year, the crime lab processed 4,138 blood samples in DUI cases. Less than half of those – 1,747 – were tested for drugs other than alcohol, because the lab generally doesn’t do drug testing when the measured blood alcohol content was above 0.1 – compared with the legal limit of 0.08. Of those samples tested for drugs, the report says 39% showed signs of THC, and 47% showed THC or one of its byproducts.

One notable trend has been a jump in samples showing multiple substances, like alcohol and marijuana. In 2021, the lab reported 127 cases where someone tested positive for both alcohol and THC and another 205 that tested positive for alcohol, THC and another drug. Those numbers were up 8% and 9%, respectively, from 2020.

“Statewide with the Montana Highway Patrol, we see the majority is ‘poly-drug use,’” said Nelson.

Pepper Petersen, president and CEO of the Montana Cannabis Guild, was one of the lead advocates for I-190. He said the state’s data backs up their contention that few drivers in Montana are being cited for marijuana impairment alone.

“What we’re seeing is that people who are traditionally impaired on something might be adding marijuana to the mix,” Petersen said. “They’re having DUIs for some reason other than marijuana; they just also happen to have marijuana in their system.”

He also noted the number of cases where samples apparently showed THC byproducts instead of the compound itself. He said those byproducts can remain in some people’s systems for as long as 30 days.

“There needs to be more scientific methodology, better evidence that presence of marijuana in the blood equals impairment,” said Petersen.

The increase in reported cases of drug-related impairment also comes as law enforcement puts a greater emphasis on finding those cases. Nelson said, for the last few years, all MHP troopers have gone through the Advanced Roadside Impaired Driving Enforcement program – a training to help them identify signs of impairment caused by something other than alcohol.

“It’s not a lot different than the alcohol detection, but our troopers are trained to determine whether the person is under the influence of another drug,” he said.

Nelson said the Yellowstone County Sheriff’s Office has also started using that type of training, and he expects other agencies to follow suit.

In addition, 27 MHP troopers – out of more than 250 statewide – are trained as “drug recognition experts.” That more extensive training is intended to teach them to do a more systematic analysis of which type of drug an impaired person has used.

The crime lab performs drug testing on all cases submitted by DREs. In 2021, 163 of those cases were submitted, and just under 100 were positive for cannabis, alone or in conjunction with other drugs.