DUI Laws in Montana

0.08 for drivers generally; 0.04 for commercial motor vehicle drivers; 0.02 for drivers under 21. 'Aggravated DUI' applies at 0.16 or more.

First DUI: 24 consecutive hours to 6 months in jail and a fine of $600 to $1,000 (48 hours to 1 year and $1,200 to $2,000 if a passenger under 16 was in the vehicle). The mandatory minimum jail term generally cannot be served on home arrest, and sentence may not be deferred. The person must complete a chemical dependency assessment and education course. The department suspends the license for 6 months; the court may recommend a probationary license with conditions such as an ignition interlock or 24/7 sobriety monitoring.

A 4th or subsequent DUI is a felony in Montana. It applies when the person has three or more prior convictions for DUI, aggravated DUI, or certain related offenses (such as vehicular homicide while under the influence or negligent vehicular assault). For a 3rd or later offense, all previous convictions count, not just those within 10 years. A conviction for vehicular homicide while under the influence (45-5-106) or vehicular assault (45-5-107) also triggers the felony penalty. Penalties: 13 months to 2 years committed to the Department of Corrections (with possible placement in a residential alcohol treatment program), followed by a 5-year suspended prison term, and a $5,000 to $10,000 fine. Repeat felony offenders can get up to 10 years in state prison.

Refusing a blood, breath or other test leads to a license suspension of 6 months for a first refusal, or 1 year for a second or later refusal within 5 years of a previous refusal, with no restricted probationary license. An administrative fee of $300 applies. The officer issues a temporary permit valid for 5 days.

10 years for second offenses: an offender is considered previously convicted if less than 10 years have passed between the current offense and a previous conviction. For a third or subsequent offense, all previous convictions are used for sentencing.

A Montana basic driver record covers a person's whole driving history, including convictions and sanctions, so a DUI stays on the driving record for life. For sentencing, prior DUIs generally count if they were within 10 years. For a 3rd or later offense, every previous conviction counts. Under Montana insurance law, a conviction older than 3 years that comes only from a driver record may not be used to set insurance rates or eligibility.

After a first DUI conviction, the court may recommend a probationary license, which can be conditioned on an ignition interlock or a 24/7 sobriety and drug monitoring program. After a second DUI, a probationary license is available only after 45 days of the 1-year suspension and with a court recommendation. No restricted probationary license is available during a test-refusal suspension.