MontanaSB 50869th Legislature, Regular Session (2025)Senate

Generally revise driving under the influence laws for THC levels in drivers under 21

Your PRIA Score

Score Hidden

Personalized for You

How does this bill affect your finances?

Sign up for a PRIA Policy Scan to see your personalized alignment score for this bill and every other piece of legislation we track. We analyze your financial profile against policy provisions to show you exactly what matters to your wallet.

Free to start

Bill Overview

Analyzed Economic Effects

5 provisions identified: 0 benefits, 3 costs, 2 mixed.

5 ng/mL THC is DUI for drivers

If your THC is 5 ng/mL or more, you are guilty of DUI. Tests must measure active THC in blood or another bodily sample, not inactive metabolites. This applies when you drive or are in actual physical control of a vehicle in Montana.

Cities can adopt and enforce DUI

Cities and towns may pass this DUI section as a local ordinance. They can enforce it locally and apply the fines and penalties in that ordinance.

Tougher DUI limits for under‑21 drivers

If you are under 21, any THC in your body counts as DUI. Tests exclude inactive metabolites. A BAC of 0.02 or more also counts as DUI. THC must be shown by a blood or other bodily sample. Alcohol can be shown by blood, breath, or other test. These rules apply while you drive or are in actual physical control in Montana.

Absolute liability, single DUI conviction rule

DUI under this section uses absolute liability. Prosecutors do not need to prove a particular mental state. You may be charged under more than one subsection, but you can be convicted of only one DUI offense for the same acts.

What BAC test numbers mean in court

If a BAC test is taken within a reasonable time after driving: 0.04 or less supports that you were not impaired. Over 0.04 but under 0.08 gives no automatic conclusion. 0.08 or more supports impairment. These are rebuttable in court and weighed with other evidence.

Sponsors & Cosponsors

Sponsor

Willis Curdy
Democrat • Senate

Cosponsors

Steven Kelly
Republican • House

Roll Call Votes

All Roll Calls

Yes: 209 • No: 88

Senate vote • 4/11/2025

Do Concur

Yes: 61 • No: 38

Senate vote • 4/11/2025

Do Concur

Yes: 62 • No: 37

Senate vote • 3/6/2025

Do Pass

Yes: 44 • No: 6