Montana THC-Positive DUI Cases Rise Sharply
The Montana State Crime Lab recorded more than twice as many THC-positive DUI toxicology cases in 2025 as it did in 2019.
Updated on Nov. 7, 2026 in Drug Crime
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The Montana State Crime Lab reported 1,046 DUI toxicology cases that tested positive for THC in 2025, up from 464 in 2019. The crime lab expanded its drug testing starting in 2024.
Why it matters
The rise in THC-positive DUI cases reflects how cannabis use intersects with impaired driving in Montana, a question that shapes enforcement and public safety efforts across the state. The figures help show how changes in testing volume can affect reported totals.
The Montana State Crime Lab recorded 1,046 THC-positive DUI cases in 2025, compared with 464 in 2019, and the share of drug-tested DUI cases positive for cannabis has remained around 40% to 50%. Whether the increase is driven by expanded testing beginning in 2024 or by other factors has not been determined.
The players
Montana State Crime Lab
The state forensic laboratory that analyzes toxicology samples from DUI investigations and reports the case totals cited in this story.
Montana Highway Patrol
The state law enforcement agency whose officers conduct traffic stops and assess drivers for signs of impairment under Montana DUI law.
The details
Montana Highway Patrol officers look for problems with speed, judgment, and staying in the correct lane during traffic stops. Montana law allows a DUI charge when an active THC level reaches five nanograms per milliliter, and drivers can also face charges if officers find them under the influence of a drug and unsafe to drive, even below that threshold.
Timeline
2019: The crime lab recorded 464 THC-positive DUI cases.
2024: The crime lab expanded drug testing of DUI cases.
2025: The crime lab recorded 1,046 THC-positive DUI cases.
Legal Context
Montana's cannabis legalization and its five-nanogram-per-milliliter active THC DUI threshold frame how these toxicology results are charged and prosecuted. The case totals arrive as the state's DUI enforcement operates under that statutory standard.
Drivers in Montana face DUI charges if an active THC level reaches five nanograms per milliliter or if officers find them impaired, even below that level. The growing number of THC-positive cases signals that impaired-driving enforcement is reaching more drivers statewide.
The takeaway
Drivers should avoid getting behind the wheel after using cannabis, since Montana can charge a DUI at five nanograms per milliliter of active THC or when officers judge a driver unsafe. Planning a sober ride in advance reduces the risk of a charge.
Further reading
For more on enforcement trends, see Drug Crime coverage across Montana.
Source note: This article includes information reported by K96 FM.
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