Montana Marijuana DUI Numbers Have More To Them Than You Think

Montana Cannabis DUI Cases Have More Than Doubled Since 2019

Much like alcohol, just because marijuana is legal doesn't mean you can use it and then get behind the wheel of a car.

Unfortunately, it looks like plenty of Montana drivers are getting behind the wheel after using marijuana, as the number of cannabis-related DUI cases has been climbing.

Montana Crime Lab Reports More Than 1,000 THC-Positive DUI Cases

According to Montana Right Now, the Montana State Crime Lab reported 464 DUI toxicology cases that tested positive for THC in 2019. By 2025, that number had climbed to 1,046.

That's more than double what the state recorded before recreational marijuana sales began. But that doesn't necessarily mean more people are driving high. There's an important detail behind those numbers.

Starting in 2024, the crime lab expanded its drug testing, meaning more DUI cases were being tested. So, when you look at the percentage of drug-tested DUI cases that came back positive for cannabis, the numbers have actually remained fairly steady at around 40% to 50%, both before and after legalization.

According to the Montana Highway Patrol, officers look for specific signs of impairment during traffic stops, including problems with speed, judgment, and staying in the correct lane.

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Montana Highway Patrol Offers Advice For Marijuana Users

MHP's field sobriety coordinator, Jesse Short, says THC can be particularly difficult to measure because the amount in someone's system doesn't always line up with how impaired they actually are.

Short says one of the biggest mistakes people make is assuming they're okay to drive just because they feel normal again.

Montana law allows officers to charge someone with DUI if their active THC level reaches five nanograms per milliliter. However, drivers can also face charges if officers determine they are under the influence of a drug and unsafe to drive, even if their THC level doesn't reach that threshold.

A lot of people don't realize how long the effects of cannabis can stick around. Short's advice is pretty simple: figure out how you're getting home before you consume marijuana, not afterward.