People are often surprised to see the word aggravated on a DUI citation. It sounds like a more serious crime, and in terms of penalties it is. But in Montana, aggravated DUI is not its own offense. It is an ordinary DUI plus one extra fact, and that extra fact is something the State has to prove. I am certified in NHTSA Standardized Field Sobriety Testing and have worked inside a local prosecutor's office, so I know how these charges are built and where the aggravating fact is most often thin. For an overview of Montana DUI law, see our Missoula DUI defense page.
The Four Triggers for Aggravated DUI
Under MCA § 61-8-1001(1), a person commits aggravated DUI by committing an impairment DUI, a 0.08 per se DUI, a 0.04 commercial vehicle DUI, a THC per se DUI, or a drug-level per se DUI (MCA § 61-8-1002(1)(a), (b), (c), (d), or (f)) and one of the following is true:
- High alcohol concentration: a BAC of 0.16 or more (§ 61-8-1001(1)(a)).
- Interlock order: you are under a court or department order to use an ignition interlock (§ 61-8-1001(1)(b)).
- Suspended for a prior DUI: your license or privilege to drive is suspended, canceled, or revoked as a result of a prior DUI (§ 61-8-1001(1)(c)).
- Refusal while already suspended: you refuse to give a breath sample as required by MCA § 61-8-1016 while your license is suspended, canceled, or revoked under an implied consent statute (§ 61-8-1001(1)(d)).
The under-21 offense (0.02 alcohol or any active THC for drivers under 21) is not on that list, so it cannot be the base for an aggravated DUI.
Aggravated DUI Penalties Under MCA § 61-8-1007(4)
The aggravated tier raises both the jail minimum and the fine. For comparison, a first per se DUI has no jail minimum and a first impairment DUI has a 24-hour minimum. Our first-offense DUI page has those figures.
| Offense | Jail and fine | With a passenger under 16 |
|---|---|---|
| First | 2 days to 1 year; $1,000 | 4 consecutive days to 1 year; $2,000 |
| Second | 15 days to 1 year; $2,500 | 45 days to 1 year; $5,000 |
| Third | 40 consecutive days to 1 year; $5,000 | 90 consecutive days to 1 year; $10,000 |
Source: MCA § 61-8-1007(4)(a). The mandatory minimum may not be served under home arrest and may not be suspended unless the judge finds that jail would pose a risk to your physical or mental well-being (§ 61-8-1007(4)(b)). A DUI sentence cannot be deferred (MCA § 61-8-1011(4)). The chemical dependency assessment, course, or treatment requirements of MCA § 61-8-1009 apply as they do to any DUI conviction.
An Aggravated Prior Follows You
If you have a prior conviction or a pending charge for a DUI that meets the aggravated definition, a new DUI is punished under the aggravated tier, even if nothing about the new arrest is aggravating (MCA § 61-8-1007(1)(c), (2)(c)). That makes the way an earlier case was resolved important, and it is one more reason to look carefully at whether the aggravating fact in a current case can actually be proven. Our second and third DUI page explains how priors are counted.
24/7 Testing Can Be Ordered on an Aggravated Charge
For most first-offense DUIs, a court cannot compel participation in the 24/7 Sobriety Program. An aggravated DUI charge changes that. A court may compel participation for a person charged with aggravated DUI (MCA § 44-4-1205(4)(a)) and may make it a condition of bond or pretrial release (§ 44-4-1205(2)(a)). The program's primary alcohol testing method is twice-a-day, in-person breath testing at a central location (MCA § 44-4-1203(2)). In practice, that means testing may start well before the case is resolved.
The statute also allows hardship alternatives, such as a transdermal monitor or a remote breath device, instead of twice-daily in-person testing (MCA § 44-4-1203(2)). And while a person is in compliance, a court may stay sanctions it imposed (MCA § 44-4-1205(1)(a)). If 24/7 is likely in your case, it is worth planning for it early, because testing times and travel can affect your work and family schedule.
Related Charges That Often Travel With Aggravated DUI
- Driving while suspended. Driving while suspended or revoked for a DUI or refusal is its own offense: 2 days to 6 months in jail, a fine up to $2,000, or both, plus up to 40 hours of community service, and MVD adds 1 year to the suspension (MCA § 61-5-212(1)(b)(iii), (2)(a)).
- Interlock violations. Driving a vehicle without a required interlock, or helping someone get around one, is punishable by a fine up to $500, up to 6 months in jail, or both (MCA § 61-8-1024(4)).
- Child endangerment. Aggravated DUI with a child under 14 in the vehicle that causes a substantial risk of death or serious bodily injury can be charged as a felony under MCA § 45-5-628(1)(e).
- Aggravated vehicular homicide. A death caused during a DUI that meets the aggravated definition can be charged under MCA § 45-5-107, which carries 3 to 30 years. See our felony DUI page.
How I Challenge the Aggravating Fact
The aggravating fact is a separate element, and it deserves its own scrutiny. Depending on the facts, I look at:
- for a 0.16 allegation, how the breath or blood result was obtained, how the instrument was maintained, and how a blood sample was drawn, stored, and tested;
- for an interlock or suspension trigger, what the MVD and court records actually show about your status on the date of the arrest;
- for a refusal trigger, whether a breath sample was properly requested under MCA § 61-8-1016 and whether an implied-consent suspension was in effect;
- the underlying DUI itself, including the stop and the field sobriety tests.
If the aggravating fact falls away, the case may be sentenced under the ordinary tiers instead. Every case turns on its own facts.
This page explains Montana law in general as of the 2025 Montana Code Annotated. It is not legal advice about your specific case.