Montana DUI Laws & Penalties
Last reviewed:
Montana recodified its DUI statutes in 2021 — penalties now at MCA §§ 61-8-1007 (1st–3rd) and 61-8-1008 (4th+), offense at § 61-8-1002. Older citations to § 61-8-714 are obsolete. Home of the 24/7 Sobriety Program.
Overview
- Legal BAC limit: 0.08% (commercial 0.04%, under-21 0.02%, enhanced at 0.16%).
- Lookback period: lifetime (for 4th-offense felony) / 10 (some enhancements). A 4th DUI is a felony counting priors for LIFE (Montana toughened this — no washout for the felony trigger).
- Primary statute: MCA § 61-8-1002 (offense); § 61-8-1007 (1st–3rd penalties); § 61-8-1008 (4th+)
0.16+ = 'aggravated DUI' (§ 61-8-465) with higher mandatory minimums; also aggravated if a passenger under 16 aboard or refusal after a prior conviction.
Penalties by offense
| Offense | Classification | Jail | Fine | License suspension | Interlock |
|---|---|---|---|---|---|
| First offense | misdemeanor | 24 hours – 6 months; mandatory min 24 hours (48 hours if aggravated 0.16+) | $600–$1,000 ($1,000 minimum if aggravated) | 6 months; hardship: probationary license possible; IID or 24/7 program conditions | Not required |
| Second offense | misdemeanor | 7 days – 1 year; mandatory min 7 days | $1,200–$2,000 | 1 year; hardship: IID-restricted after portion; 24/7 program | Required |
| Third offense | misdemeanor | 30 days – 1 year; mandatory min 30 days | $2,500–$5,000 | 1 year; hardship: IID-restricted; 24/7 program | Required |
| Fourth+ offense | felony (4th, lifetime lookback) | 13 months (Dept. of Corrections) – 5 years; mandatory min 13 months | $5,000–$10,000 | 1 year+ – years; hardship: IID required | Required |
First offense
- Classification: misdemeanor
- Jail: 24 hours – 6 months; mandatory min 24 hours (48 hours if aggravated 0.16+)
- Fine: $600–$1,000 ($1,000 minimum if aggravated)
- License suspension: 6 months; hardship: probationary license possible; IID or 24/7 program conditions
- Alternative disposition: Mandatory ACT (Assessment, Course, Treatment) evaluation; 24/7 Sobriety Program (twice-daily breath tests or CAM bracelet) frequently ordered.
- Interlock: IID or 24/7 Sobriety Program participation is common as a condition; IID mandatory on repeats/aggravated.
Second offense
- Classification: misdemeanor
- Jail: 7 days – 1 year; mandatory min 7 days
- Fine: $1,200–$2,000
- License suspension: 1 year; hardship: IID-restricted after portion; 24/7 program
- Vehicle seizure/forfeiture possible; 24/7 Sobriety Program common.
Third offense
- Classification: misdemeanor
- Jail: 30 days – 1 year; mandatory min 30 days
- Fine: $2,500–$5,000
- License suspension: 1 year; hardship: IID-restricted; 24/7 program
Fourth+ offense
- Classification: felony (4th, lifetime lookback)
- Jail: 13 months (Dept. of Corrections) – 5 years; mandatory min 13 months
- Fine: $5,000–$10,000
- License suspension: 1 year+ – years; hardship: IID required
- Per § 61-8-1008.
Refusing a chemical test (implied consent)
Refusal: 6-month suspension first (1 year for subsequent); officer typically obtains a warrant for blood. Refusal after a prior conviction = aggravated DUI. Refusal admissible.
Statute: MCA § 61-8-1016
Ignition interlock
IID and/or the 24/7 Sobriety Program (twice-daily breath tests or continuous alcohol monitoring) are the signature Montana sanctions; IID mandatory on repeat/aggravated convictions.
Statute: MCA § 61-8-1027; Title 44 ch. 4 part 12 (24/7)
Frequently asked questions
What is the penalty for a first DUI in Montana?
A first DUI in Montana is a misdemeanor. Jail: 24 hours – 6 months; mandatory min 24 hours (48 hours if aggravated 0.16+). Fine: $600–$1,000 ($1,000 minimum if aggravated). License suspension: 6 months; hardship: probationary license possible; IID or 24/7 program conditions.
What is the legal BAC limit in Montana?
0.08% for most drivers, 0.04% for commercial drivers, and 0.02% for drivers under 21.
How long does Montana look back at prior DUI offenses?
lifetime (for 4th-offense felony) / 10 (some enhancements). A 4th DUI is a felony counting priors for LIFE (Montana toughened this — no washout for the felony trigger).