## What happens after a first-offense DUI in Montana? In Montana, the legal BAC limit is **0.08**. Drivers under 21 are subject to a near-zero limit. Commercial drivers are limited to 0.04. If you're charged with a first DUI, here's the framework. ### Classification Misdemeanor. ### Jail 24 hours to 6 months (24-hour mandatory minimum). ### License suspension 6 months. ### Ignition interlock device (IID) Required for at least 1 year if seeking a restricted license. ## What aggravators do The framework above describes a basic, no-aggravator first offense. The penalties get worse — fast — when any of these are present: - **High BAC** — most states pile on extra mandatory jail and IID time once BAC crosses 0.15 or 0.20 - **Child in the vehicle** — many states elevate the charge or add mandatory jail - **Accident, especially with injury** — can convert a misdemeanor into a felony - **Refusing the breath/blood test** — usually triggers a longer license suspension on its own, separate from the criminal case ## You're fighting two cases, not one A DUI/DWI arrest sets two parallel processes in motion: 1. **The criminal case** — where the prosecutor has to prove you were impaired beyond a reasonable doubt. 2. **The administrative license case** — handled by the state DMV/MVD, with a much lower burden of proof and a tight deadline (often 7–30 days from arrest) to request a hearing or you lose your license by default. Missing the administrative deadline is one of the most common, costly mistakes. Talk to a lawyer immediately, not after your court date. ## Diversion, deferred adjudication, and pretrial alternatives Many states (and many local prosecutors in Montana) offer first-offense alternatives — diversion, deferred judgment, ARD, 24D, treatment programs — that can avoid a permanent conviction. Eligibility is fact-specific (BAC, driving history, accident, refusal). A local DUI defense attorney will know what your county's prosecutor offers. ## What you should do Don't plead guilty at your first appearance without talking to a lawyer. DUI cases have technical defenses (calibration of the breath device, traffic-stop legality, blood-draw chain of custody, field-sobriety test administration) that can change the outcome. Most Montana DUI defense attorneys offer free consultations. --- *This guide is general information about Montana DUI law as of early 2026 and is not legal advice. Penalties shift, prosecutors have discretion, and your specific facts will change the analysis. Talk to a licensed Montana criminal-defense attorney about your case before making decisions.*