A fourth DUI in Montana is a felony. Conviction carries a mandatory sentence of 13 months to two years in Department of Corrections custody, a fine between $5,000 and $10,000, a one-year driver’s license suspension, and a five-year suspended prison term that hangs over you afterward.1Montana State Legislature. Montana Code 61-8-1008 – Penalty for Driving Under Influence – Fourth and Subsequent Offenses Because the offense is a felony punishable by more than a year of incarceration, the conviction also strips your firearm rights under federal law and creates lasting problems with travel, employment, and licensing.
Why Old Convictions Still Count
Montana uses a lifetime lookback for fourth-offense DUI. There is no expiration date on prior convictions.2Montana Department of Justice. Montana Prosecutor’s DUI Handbook A DUI from 1995 counts the same as one from last year. Second-offense DUI uses a 10-year window, but that window disappears entirely once you reach the third and fourth offense.
The prior convictions that count toward a fourth offense include standard DUI, aggravated DUI, negligent homicide committed while driving under the influence, and negligent vehicular assault. A single prior vehicular homicide conviction involving intoxication can elevate your current charge to felony status on its own. Out-of-state convictions count if the underlying offense is substantially similar to Montana’s DUI laws.1Montana State Legislature. Montana Code 61-8-1008 – Penalty for Driving Under Influence – Fourth and Subsequent Offenses
The Prison Sentence
Montana law gives the judge two sentencing tracks for a fourth DUI.1Montana State Legislature. Montana Code 61-8-1008 – Penalty for Driving Under Influence – Fourth and Subsequent Offenses
Standard Track
Under the standard track you receive a mandatory term of not less than 13 months and not more than two years with the Department of Corrections, for placement in a correctional facility or program. That sentence cannot be deferred, suspended, or paroled. On top of the mandatory term, the court imposes a consecutive five-year suspended sentence to Montana State Prison or the Montana Women’s Prison. You do not serve the suspended portion unless you violate the conditions of your release.
If you complete a residential alcohol treatment program approved by the Department of Corrections during the mandatory term, the remainder of the 13-month to two-year sentence converts to supervised probation. Completing treatment can shorten your time in a correctional facility, but the five-year suspended sentence remains.
Treatment Court Track
Alternatively, the court may sentence you to up to five years in an appropriate treatment court program. You must complete the program. A suspended sentence is possible under this track, but the court cannot defer imposition of sentence. The fine range, $5,000 to $10,000, is the same either way.
What It Actually Costs
The base fine is $5,000 to $10,000, but the financial hit reaches well beyond that.1Montana State Legislature. Montana Code 61-8-1008 – Penalty for Driving Under Influence – Fourth and Subsequent Offenses Montana requires you to pay the costs of imprisonment, probation, and alcohol treatment if you are financially able. Court costs, supervision fees, treatment tuition, and drug testing fees stack on top of the fine. If your offense caused property damage or injury, the court can order restitution.
After conviction you must file an SR-22 certificate of financial responsibility, which is proof you carry the state-mandated minimum auto insurance. SR-22 filings typically last three years and mark you as a high-risk driver, which commonly doubles or triples annual premiums. Add the monthly cost of leasing and maintaining an ignition interlock device, and the total burden of a fourth DUI can reach tens of thousands of dollars beyond the fine.
License Suspension and Ignition Interlock
A fourth DUI triggers a one-year license suspension. For the first 90 days you cannot obtain any form of driving privileges. After that, the court may recommend a probationary license, but only if you meet the requirements of Montana’s ignition interlock statute.3Montana State Legislature. Montana Code 61-5-208 (2025) – Period of Suspension or Revocation – Limitation on Issuance of Probationary License
The suspension does not lift automatically when the year ends. If you have not completed the required chemical dependency treatment, your license stays suspended until you do. The clock does not save you.
For any second or subsequent DUI conviction, the court must restrict you to driving only a vehicle equipped with a functioning ignition interlock device for the entire probationary period. You pay for the device, including leasing, installation, and monthly calibration fees.4Montana State Legislature. Montana Code 61-8-1010 – Driving Under Influence – Ignition Interlock Device Tampering with the device creates additional legal problems on its own.
Montana law also includes provisions for forfeiting a vehicle used during a DUI offense. A vehicle forfeited under the ignition interlock statute must be seized by the arresting agency within 10 days after conviction. It is not automatic, but it is an available tool, and prosecutors are more likely to pursue forfeiture against someone on a fourth offense.
Probation Conditions
Probation after a fourth DUI is not the light-touch supervision people sometimes expect from earlier misdemeanor cases. The court imposes mandatory conditions that govern your daily life for years:
- Complete ban on alcohol consumption, not moderation.
- No entering bars or other establishments where alcoholic beverages are served.
- No driving without your probation officer’s specific authorization, and only in a vehicle equipped with an ignition interlock device.
- Enrollment and continued participation in an aftercare treatment program for the entire probationary period.
- Random drug and alcohol testing, both routine and unannounced.
- Payment of the costs of imprisonment, probation, and treatment if you are financially able.
Violating any of these conditions can activate the five-year suspended prison sentence from your original judgment.1Montana State Legislature. Montana Code 61-8-1008 – Penalty for Driving Under Influence – Fourth and Subsequent Offenses Judges routinely revoke probation and impose the suspended time when offenders fail drug tests, miss check-ins, or are found in a bar. On a fourth DUI, courts have little patience for noncompliance.
Consequences That Outlast the Sentence
The reclassification from misdemeanor to felony creates a set of consequences that follow you long after you finish the sentence.
Firearm Rights
Federal law prohibits anyone convicted of a crime punishable by imprisonment for more than one year from possessing firearms or ammunition. A fourth DUI in Montana carries a mandatory 13 months to two years, which puts it squarely within the prohibition.5Office of the Law Revision Counsel. 18 USC 922 – Unlawful Acts The prohibition applies nationwide and remains in force unless your rights are formally restored through a pardon or expungement.
Travel to Canada
Canada treats impaired driving as a serious criminal offense and routinely denies entry to travelers with DUI convictions. Since December 2018, Canada has classified impaired driving as a serious crime, making entry substantially harder for anyone convicted after that date. People with felony DUI convictions generally cannot enter Canada without either a Temporary Resident Permit or completion of the formal Criminal Rehabilitation process, both of which require extensive documentation and fees.6Government of Canada. Overcome Criminal Convictions If you live near the border or travel to Canada for work, this restriction has immediate practical impact.
Employment and Professional Licensing
A felony record shows up on background checks and can disqualify you from jobs in law enforcement, education, healthcare, government, and any position requiring a professional license. Commercial driving privileges are separately affected, with federal disqualification periods that apply on top of Montana’s state-level penalties. Many employers and licensing boards require disclosure of felony convictions, and some have mandatory disqualification provisions.
Defenses That Can Drop the Charge
A felony DUI charge is not automatically a felony conviction. At the fourth-offense level, the defenses that matter most tend to be technical.
Challenging the Stop and Arrest
Law enforcement must have reasonable suspicion to pull you over and probable cause to arrest you. If the officer lacked a legitimate reason for the initial stop, everything that followed can be challenged. Dashcam and bodycam footage often tells a different story than the police report. When stop evidence gets suppressed, the BAC results and field sobriety observations usually go with it.
BAC Testing Accuracy
Montana requires strict compliance with procedural protocols for breath, blood, and oral fluid testing. Common grounds for challenging results include improper calibration of the breath device, failure to observe the required waiting period, chain-of-custody problems with blood samples, and questions about whether the person administering the test was properly trained. Maintenance records and lab accreditation documents are standard targets for the defense.
Attacking the Prior Convictions
Because a felony charge depends on three qualifying prior convictions, challenging the validity of those priors is a defense specific to repeat-offense cases. If a prior was obtained without proper representation, without a valid guilty plea, or in a proceeding that violated your constitutional rights, it may not count toward the total. Knocking even one prior off the list drops the charge from a felony fourth to a misdemeanor third, which carries dramatically lower penalties.7Montana State Legislature. Montana Code 61-8-1007 – Penalty for Driving Under Influence – First Through Third Offenses
Sentencing Mitigation
If conviction is unavoidable, sentencing becomes the focus. Judges have discretion within the statutory range. Voluntary enrollment in treatment before sentencing, documented sobriety, participation in support groups, and stable employment all support an argument for the lower end of the range or for the treatment court track rather than standard correctional placement. The absence of aggravating circumstances like crashes, injuries, or an extremely high BAC also helps.