Montana DUI Laws Explained

In the state of Montana, the offense of drunk driving is referred to as "Driving Under the Influence" (DUI). Pursuant to Montana's DUI law, it is unlawful for a person who is under the influence of alcohol to drive or be in actual physical control of a vehicle upon the ways of the state open to the public. Unlike the law in other states, in Montana the term "vehicle" does not include a bicycle.

Additional Montana DUI offenses

DUI DRUGS - It is unlawful for a person to drive or be in actual physical control of a vehicle within the state of Montana if that person is under the influence of a dangerous drug, any other drug, or alcohol and any dangerous or other drug.

DRIVING WITH EXCESSIVE ALCOHOL CONCENTRATION (PER SE DUI) - It is unlawful for any person to drive or be in actual physical control of a noncommercial vehicle upon the way of the state open to the public while the person's blood alcohol content (BAC) is .08 or more.

COMMERCIAL VEHICLES - It is unlawful to drive or be in actual physical control of a commercial motor vehicle upon the ways of the state open to the public while a person's BAC is .04 or more.

MINORS - Persons under the age of 21 who have a BAC of .02 or more are prohibited from driving or being in actual physical control of a vehicle upon the ways of the state open to the public.

**NOTE - The fact that a person was entitled to use alcohol or a drug does not constitute a defense to a Montana DUI charge.

"Under the influence" means that as a result of taking into the body alcohol, drugs, or any combination of alcohol and drugs, a person's ability to safely operate a vehicle has been diminished.

Montana DUI Law and Alcohol Test Results

Persons who submit to a chemical test that reveals a blood alcohol content (BAC) of .04 or less will be inferred to have not been under the influence of alcohol. Persons with a BAC of .08 or more will be inferred to be under the influence; however, that inference is refutable.