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Montana DUI Laws

Montana DUI Defense

What you're facing, what the deadlines are, and the questions your attorney needs to answer — specific to Montana (MT) law.

BAC Limit

0.08

Enhanced BAC

0.16

Higher penalties above this

Lookback Period

10 years

Prior offenses count within

First Offense Penalties in Montana

Jail TimeUp to 6 months (mandatory 24 hours if BAC 0.16+)
Fines$600 – $1,000
License Suspension6 months
Ignition InterlockRequired for BAC 0.16+

Implied Consent & Test Refusal

Like all 50 states, Montana has an implied consent law — by driving on Montana roads, you've already agreed to submit to a chemical test (breath, blood, or urine) if an officer has probable cause to believe you're impaired.

Refusal Penalty

6-month license suspension

Montana-Specific Detail

Montana has no mandatory minimum jail time for a standard first-offense DUI (under 0.16 BAC). The state does require a chemical dependency assessment and completion of a treatment course.

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DUI Defense Playbook — $97

26 questions your DUI attorney hopes you never ask, a case stage roadmap, red flag checklist, and a case progress scorecard. Instant PDF download — calibrated for Montana DUI defendants.

Get the DUI Playbook — $97Read the Free DUI Guide

Important: This page provides general legal information about Montana DUI laws as of the date of publication. Laws change frequently. This is not legal advice. Consult a Montana-licensed attorney for guidance specific to your case.