DUI Laws in Montana (DUI)
Montana uses the term "DUI" for impaired driving offenses. The standard BAC limit is 0.08%. The lookback period is Lifetime. 4th offense (felony. Below are the full details of Montana's DUI laws and penalties.
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Overview
Montana takes an increasingly tough stance on impaired driving, with penalties that escalate sharply after a first offense. The state uses a lifetime lookback period, meaning any prior DUI conviction — no matter how old — counts toward enhancing future penalties. Montana is one of few states that treats a fourth DUI as a felony regardless of time elapsed. A 24/7 sobriety monitoring program and mandatory alcohol treatment are central features of the state's approach to repeat offenders.
Official term: DUI
BAC Limits
| Driver Type | BAC Limit |
|---|---|
| Standard (21+) | 0.08% |
| Commercial (CDL) | 0.04% |
| Under 21 | 0.02% |
| Enhanced Penalty | No separate enhanced BAC tier; aggravated penalties apply based on other factors such as excessive speed, minor passengers, or prior offenses |
Penalties by Offense
| Offense | Classification | Jail Time | Fines | License Suspension | IID |
|---|---|---|---|---|---|
| 1st Offense | Misdemeanor | Up to 6 months; a 24-consecutive-hour mandatory minimum (MCA 61-8-1007(1)) | $600 to $1,000 plus surcharges and assessments (doubled to $1,200–$2,000 with a passenger under 16) | 6 months | A judge may grant a restricted probationary license during the suspension with an IID installed; after a second or subsequent DUI, restricted licenses are generally limited to DUI treatment court participants (MCA 61-5-208) |
| 2nd Offense | Misdemeanor | 7 days to 1 year; mandatory minimum 7 days for an under-the-influence conviction — the per se 0.08% count carries a 5-day minimum — and it cannot be suspended (MCA 61-8-1007(1)-(2)) | $1,200 to $2,000 plus surcharges ($2,400–$4,000 with a passenger under 16) | 1 year | An IID is required on any restricted/probationary license; after a second DUI, a probationary license is generally available only through DUI treatment court participation |
| 3rd Offense | Misdemeanor | 30 days to 1 year; mandatory minimum 30 days (cannot be suspended) | $2,500 to $5,000 plus surcharges ($5,000–$10,000 with a passenger under 16) | 1 year | An IID is required on any restricted/probationary license; probationary licenses after a third DUI are generally limited to DUI treatment court participants |
| Felony | Felony | First felony DUI (4th offense): 13 months to 2 years plus a suspended consecutive 5-year prison term, or up to 5 years in a treatment court program (MCA 61-8-1008(1)). Later felony DUIs escalate: up to 10 years, then up to 25 years, then a non-suspendable 5-to-25-year term (61-8-1008(2)-(4)) | $5,000 to $10,000 plus surcharges | 1 year; must complete treatment and IID requirements before reinstatement | Probation conditions after a felony sentence include ignition interlock use, abstinence, random testing, and aftercare (MCA 61-8-1008(1)(b)) |
Felony threshold: 4th offense (felony, MCA 61-8-1008; lifetime lookback — all prior DUI convictions count regardless of when they occurred). Lookback period: Lifetime — all prior DUI convictions count toward enhancement regardless of when they occurred.
Additional Penalty Details
| Offense | Community Service | Probation | DUI School |
|---|---|---|---|
| 1st Offense | Up to 40 hours at court's discretion | Up to 6 months; typically includes chemical dependency assessment | Mandatory alcohol education course (ACT — Alcohol Course for Treatment) or equivalent approved program |
| 2nd Offense | Up to 80 hours at court's discretion | Up to 1 year; chemical dependency treatment required | Mandatory chemical dependency treatment program |
| 3rd Offense | Up to 120 hours at court's discretion | Up to 1 year; intensive chemical dependency treatment required | Mandatory chemical dependency treatment; may include residential treatment |
| Felony | At court's discretion | Up to the remainder of the sentence; chemical dependency treatment mandatory | Mandatory chemical dependency treatment; residential treatment likely required |
Implied Consent Law
Under Montana's implied consent law (MCA § 61-8-1016), any person operating a vehicle on Montana roads is deemed to have consented to a test of blood, breath, or urine for alcohol or drugs when requested by law enforcement with reasonable cause.
Refusal penalties: First refusal: 6-month license suspension. Second or subsequent refusal: 1-year license suspension. The refusal can be used as evidence against the driver in court and bars any restricted probationary license during the suspension (MCA 61-8-1032(2)(f)).
Aggravating Factors
| Factor | Impact |
|---|---|
| Minor passenger under age 16 | Moves you to the doubled penalty tier — first offense becomes 48 hours to 1 year and $1,200–$2,000; second becomes a 14-day minimum and $2,400–$4,000; third becomes a 60-day minimum and $5,000–$10,000 (MCA 61-8-1007(1)) |
| BAC of 0.16% or higher | Aggravated DUI — punished on a separate aggravated tier (first offense: 2-day mandatory minimum and $1,000 minimum fine; MCA 61-8-1007(4), definition in 61-8-1001) |
| Excessive speed (20+ mph over limit) | Additional reckless driving charges; increased jail time and fines |
| Driving on a suspended or revoked license | Separate misdemeanor charge; additional 6 months to 2 years jail and extended license revocation |
| Causing bodily injury or death | Upgraded to vehicular assault (felony) or negligent vehicular homicide with up to 30 years imprisonment |
| Refusal to submit to chemical testing | Automatic license suspension and refusal admitted as evidence at trial |
DUI with Injury
Classification: Felony — Vehicular Assault While Under the Influence (MCA § 45-5-106)
Up to 5 years in state prison and/or up to $10,000 in fines for vehicular assault. Negligent vehicular homicide (MCA § 45-5-104) while intoxicated carries up to 30 years imprisonment and up to $50,000 in fines. Restitution to victims is mandatory.
Underage DUI
Drivers under 21 with BAC of 0.02% to 0.07% face a 90-day license suspension for a first offense, 6 months for a second, and 1 year for a third or subsequent (MCA 61-8-1007(3)). BAC of 0.08% or higher subjects the underage driver to the same adult DUI penalties. Alcohol education course is mandatory for all underage offenses.
Diversion Programs
Program: Deferred Prosecution / Treatment Court (DUI Court)
Montana offers DUI Treatment Courts in several judicial districts as an alternative to traditional sentencing. Participants undergo intensive supervision, regular drug and alcohol testing, mandatory treatment, and court appearances over 12 to 18 months. The state also allows deferred imposition of sentence for first-time offenders at the judge's discretion.
Eligibility: DUI Treatment Courts generally target repeat offenders with substance use disorders. Deferred imposition of sentence is typically available only for first-time DUI offenders with no aggravating factors. Eligibility varies by judicial district.
How Long a DUI Stays on Your Record
A DUI conviction remains on your Montana criminal record permanently unless expunged. On your driving record, DUI convictions are maintained by MVD for at least 5 years for point purposes but remain visible indefinitely. Montana does not have a general DUI expungement statute, though deferred sentences that are successfully completed may be dismissed and eligible for limited record restriction.
Key Statutes
- MCA § 61-8-1002
- Driving under the influence of alcohol or drugs — main DUI statute
- MCA § 61-8-1016
- Implied consent to testing for alcohol or drugs
- MCA § 61-8-1007
- Penalty for first through third DUI offense, including aggravated-DUI tiers
- MCA § 61-8-1008
- Penalty for fourth or subsequent DUI offense (felony)
- MCA § 61-5-208
- License suspension upon DUI conviction; restricted probationary licenses
- MCA § 45-5-106
- Vehicular assault while under the influence
- MCA § 45-5-104
- Negligent vehicular homicide
Frequently Asked Questions
How long does a DUI stay on your record in Montana?
Is a first DUI a felony in Montana?
What happens if you refuse a breathalyzer in Montana?
How many DUIs is a felony in Montana?
Can you get a restricted license after a DUI in Montana?
What is Montana's 24/7 Sobriety Program?
Do I need an SR-22 after a DUI in Montana?
Can a DUI be expunged in Montana?
Related Guide
DUI license recovery in Montana→Step-by-step guide to getting your license back after a DUI in Montana — suspension periods, IID requirements, SR-22 insurance, reinstatement fees, and process.
Take Action — Direct Links
- Montana Motor Vehicle Division — DUI Information
Official Montana DOJ Motor Vehicle Division site for license reinstatement, SR-22 requirements, and DUI administrative actions
- Montana Legal Services Association
Free legal help for low-income Montanans, including guidance on DUI consequences and record issues
- Montana 24/7 Sobriety Program
Information on Montana's mandatory sobriety monitoring program for DUI offenders
- Montana Code Annotated — Title 61, Chapter 8
Full text of Montana DUI statutes including penalties, implied consent, and IID requirements
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