Minor in possession and under-21 DUI are two different charges in Montana. MIP is about a person under 21 having or drinking alcohol. Under-21 DUI is about a person under 21 driving with a small amount of alcohol, or any active THC, in the body. They sit in different parts of the code, the State proves them differently, and they affect a driver's license differently. This page compares them. It is part of our Montana DUI Guide, and it builds on our under-21 DUI page.
What Each Charge Requires
MIP. A person under 21 commits possession of an alcoholic beverage by knowingly consuming, using, possessing, or delivering or distributing one without payment (MCA § 45-5-638(1)). No car is needed. The statute also says a person may not be arrested or charged solely for being at a place where other people were drinking.
Under-21 DUI. A person under 21 commits this offense by driving or being in actual physical control of a vehicle within the state with an alcohol concentration of 0.02 or more, or with any amount of THC in the body, not counting inactive metabolites (MCA § 61-8-1002(1)(e)). The THC part took effect October 1, 2025. The State does not have to prove the driver was impaired, and it does not have to prove any mental state, because the DUI statute imposes absolute liability (MCA § 61-8-1002(5)).
Side by Side
| Question | MIP | Under-21 DUI |
|---|---|---|
| Statute | MCA § 45-5-638 | MCA § 61-8-1002(1)(e), punished under § 61-8-1007(3) |
| What the State must prove | A person under 21 knowingly consumed, used, possessed, or gave away an alcoholic beverage | A person under 21 drove or was in actual physical control of a vehicle with an alcohol concentration of 0.02 or more, or any active THC |
| Is a vehicle involved? | No | Yes, a vehicle anywhere within the state |
| Mental state | Knowingly | None required (absolute liability, § 61-8-1002(5)) |
| Fine, first offense | $100 to $300 | $100 to $500 |
| Community service, first offense | 20 hours | None stated |
| Driver's license, first offense | Under 18: confiscated by the court for 30 days. No license term is listed for ages 18 to 20. | Suspended by the Motor Vehicle Division for 90 days, at any age under 21 |
| Course or assessment | Community-based substance abuse information course | Chemical dependency assessment, plus the course or treatment under § 61-8-1009 |
Both statutes raise the penalties for a second and a third offense. A third or later MIP for a person 18 or older can include up to 6 months in county jail, in the court's discretion (MCA § 45-5-638(3)(c)). A second under-21 DUI for a person 18 or older can include up to 10 days, and a third can include 24 consecutive hours to 60 days (MCA § 61-8-1007(3)(a)).
The License Consequences Are Not the Same
This is where the two charges differ most in daily life. An under-21 DUI conviction leads to a suspension by the Motor Vehicle Division: 90 days for a first conviction, 6 months for a second, and 1 year for a third or later (MCA § 61-8-1007(3)(a)(iv)(B)). A restricted or probationary license is not available until the reinstatement fee is paid and, for a driver who was under 18, at least 30 days of the suspension have been served.
An MIP works through the court instead. For a person under 18, the court confiscates the license for 30 days on a first offense and 6 months on a second or third (MCA § 45-5-638(2)(a)). If that person does not finish the required course, the court must order a longer suspension (MCA § 45-5-638(2)(b)). The penalties listed for a person 18 or older do not include a license term.
Testing and Refusal Apply Only to the DUI
Montana's implied consent law covers the under-21 offense. An officer with particularized suspicion that a driver under 21 has violated § 61-8-1002(1)(e) can direct a breath, blood, or oral fluid test (MCA § 61-8-1016(2)(a)(ii)). A refusal brings its own suspension of 6 months with no probationary license (MCA § 61-8-1032(4)(a)). That is longer than the 90-day suspension that follows a first under-21 DUI conviction, and it applies whether or not a conviction follows. Our test refusal page explains the 30-day window to challenge it.
The MIP statute has no testing or refusal rule of its own. An MIP case usually rests on what the officer saw, what was found, and what the young person said.
When Both Are Charged From One Stop
A driver under 21 who is stopped after drinking may leave with two citations. Montana's general rule is that when the same transaction may establish more than one offense, a person can be prosecuted for each (MCA § 46-11-410(1)). The same section then limits convictions, for example where one offense is included in the other (MCA § 46-11-410(2)). The statutes do not say how an MIP and an under-21 DUI interact, so whether both can end in a conviction is a legal question about your particular charges.
Within the DUI statute the rule is clearer. A person may be convicted of only one offense under § 61-8-1002 for one incident (MCA § 61-8-1002(6)).
When the Charge Is an Adult DUI Instead
The under-21 offense is not a ceiling. The impairment offense and the 0.08 per se offense apply to any person, with no age limit in the text (MCA § 61-8-1002(1)(a) and (b)). A 19-year-old at 0.08 or more can be charged with the adult offense, with the adult penalties and a conviction that does count as a prior. Which charge the State filed is the first thing to read on the citation. Our first-offense DUI page sets out the adult penalties.
One note on other substances. Section 45-5-638 covers alcohol only. A separate statute, MCA § 45-5-624, covers a person under 21 with an intoxicating substance other than alcohol or marijuana. Older articles that cite § 45-5-624 for alcohol MIP are out of date. For driving, the under-21 DUI statute treats any active THC the same way it treats 0.02 alcohol.
Which Court, and What to Do First
For a person under 18, justice, municipal, and city courts share jurisdiction with the youth court over alcoholic beverage violations (MCA § 41-5-203(2)). Our page on DUI charges for drivers under 18 covers that age group, and our page for college students covers what a school may do. In every case, note the court date on each citation, keep all of the paperwork together, and check whether a license deadline is running.
This page explains Montana law in general as of the 2025 Montana Code Annotated. It is not legal advice about your specific case.