This guide is for general information only and is not legal advice. Laws change — verify current rules with your state DOT or a licensed attorney before relying on this for any legal matter. Read full disclaimer.
The rule
In Montana, the DUI statute does not apply to bicyclists — it covers motor-vehicle operators only. Montana's DUI statute (MCA § 61-8-1002) applies to anyone in actual physical control of a 'vehicle' on a way of the state open to the public. MCA § 61-1-101 separately defines 'bicycle' and excludes human-powered devices from the operative definition of 'motor vehicle' for DUI purposes; in practice Montana law enforcement does not charge cyclists with DUI. Open-container and disorderly-conduct charges remain available. See MCA § 61-8-1002 (Persons under the influence).
A DUI charge isn't on the table for cyclists in Montana, but that's not a license to ride drunk — public-intoxication, reckless-conduct, and disorderly-conduct charges can still apply, and cycling impaired dramatically raises crash risk.