Yes, you can be charged with DUI in Montana after testing below 0.08. The 0.08 limit is only one of the ways the State can prove the offense. The other is impairment, and it has no minimum number. This page explains how a below-the-limit case is built and how it is contested. It is part of our Montana DUI Guide.
The Charge That Does Not Need a Number
A person commits DUI by driving, or being in actual physical control of, a vehicle on the ways of this state open to the public "while under the influence of alcohol, any drug, or a combination of alcohol and any drug" (MCA § 61-8-1002(1)(a)). "Under the influence" means that, as a result of taking alcohol or drugs into the body, "a person's ability to safely operate a vehicle has been diminished" (MCA § 61-1-101).
Nothing in that definition mentions 0.08. The word is diminished, not destroyed, and the State does not have to show a crash or dangerous driving. It does have to prove the diminished ability beyond a reasonable doubt. Our page on what "under the influence" means covers the definition in detail.
What a Test Result Under 0.08 Does in Court
In an alcohol impairment case, the statute tells the judge or jury what may be inferred from a test taken within a reasonable time after the driving:
| Result at the time of the test | What the statute says | MCA |
|---|---|---|
| 0.04 or less | It may be inferred that the person was not under the influence of alcohol. | § 61-8-1002(2)(a) |
| Above 0.04 and below 0.08 | No inference either way. The result may be considered with other competent evidence. | § 61-8-1002(2)(b) |
| 0.08 or more | It may be inferred that the person was under the influence of alcohol. The inference is rebuttable. | § 61-8-1002(2)(c) |
An inference is a deduction the trier of fact may make from the evidence (MCA § 26-1-501). It is permission, not a command. A jury is never required to draw one, and the statute adds that these inferences do not limit "any other competent evidence" on whether the person was under the influence (MCA § 61-8-1002(3)).
So a 0.03 gives the defense a statutory inference to argue. A 0.06 gives neither side one. And a result under 0.08 takes away the State's easiest path, which is the 0.08 per se offense.
Drivers With a Lower Limit
For some drivers, "under 0.08" is still over the line that applies to them:
- Commercial drivers. The limit is 0.04 while driving a commercial motor vehicle (MCA § 61-8-1002(1)(c)). See CDL DUI.
- Drivers under 21. The limit is 0.02, and since October 1, 2025, any amount of active THC also counts (MCA § 61-8-1002(1)(e)). See under-21 DUI.
When Drugs Are Part of the Picture
A low alcohol result often leads an officer to suspect something else. The impairment offense covers "any drug," and the statute defines a drug as any substance that can impair a person's ability to operate a vehicle safely (MCA § 61-8-1001(7)). That includes lawful prescriptions and over-the-counter medicine.
There is a safeguard. A person may not be convicted of an impairment DUI based on the presence of a drug unless some other competent evidence tends to establish that the person was under its influence while driving (MCA § 61-8-1018(1)(a)). See alcohol and drug combinations.
How the State Tries to Prove Impairment
- The driving. What the officer says led to the stop, and what the video shows.
- Personal contact. Odor, speech, eyes, balance, and how you handled your license and paperwork.
- Field sobriety tests. A report of a physical or psychomotor assessment is admissible only if made by a person trained by, or with training recognized by, the Department of Justice (MCA § 61-8-1018(1)(c)).
- Your statements. Including the answer to "how much have you had tonight?"
- The test result itself. Even a result under 0.08 is admissible as a measured amount of alcohol (MCA § 61-8-1018(1)(a)).
How These Cases Are Defended
With no number over the limit, the State's case is a set of human observations. The defense tests each one.
- The stop. An officer needs particularized suspicion to stop a vehicle (MCA § 46-5-401). See challenging the traffic stop.
- The video against the report. Body and dash camera footage sometimes shows steadier speech and balance than the written narrative suggests.
- The field tests. Whether they were given as the officer was trained, on a fair surface, to a person without an injury, illness, or fatigue that explains the result. See field sobriety tests.
- Other explanations. Tiredness, anxiety, a medical condition, or the hour of the night can account for much of what an officer writes down.
- The statutory inference. At 0.04 or less, the defense can ask the jury to infer that alcohol was not the cause.
None of this means a below-the-limit charge is weak in every case. Some are supported by clear video of poor driving and poor balance. Whether yours is depends on the evidence, which is why reviewing it comes first.
This page explains Montana law in general as of the 2025 Montana Code Annotated. Every case turns on its own facts. It is not legal advice about your specific case.