A first DUI in Montana is generally classified as 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
Ignition interlock: Not required at this level — IID or 24/7 Sobriety Program participation is common as a condition; IID mandatory on repeats/aggravated.
Alternative disposition: Mandatory ACT (Assessment, Course, Treatment) evaluation; 24/7 Sobriety Program (twice-daily breath tests or CAM bracelet) frequently ordered.
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).
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