For someone who drives for a living, a DUI arrest raises a question that goes beyond fines and jail: will I still have a job? Montana's commercial driver rules follow federal commercial-driver standards, and they are stricter than the rules for other drivers in several ways. I am certified in NHTSA Standardized Field Sobriety Testing and have worked inside a local prosecutor's office, and I approach CDL cases knowing that the disqualification can matter as much as the criminal sentence. This page explains how Montana law treats commercial drivers. For the criminal side in general, see our Missoula DUI defense page.
The 0.04 Limit in a Commercial Motor Vehicle
Montana makes it a DUI to drive or be in actual physical control of a commercial motor vehicle with an alcohol concentration of 0.04 or more (MCA § 61-8-1002(1)(c)). That is half the 0.08 per se limit that applies in a noncommercial vehicle (MCA § 61-8-1002(1)(b)). The other DUI theories still apply to CDL holders too: impairment by alcohol or drugs (MCA § 61-8-1002(1)(a)), the 5 ng/mL THC level (MCA § 61-8-1002(1)(d)), and the drug levels added in 2025 (MCA § 61-8-1002(1)(f)).
Major Offenses That Disqualify a CDL
Montana's CDL statute lists "major offenses" that lead to disqualification. They include (MCA § 61-8-802(2)):
- refusing a test under any implied consent law;
- DUI in any vehicle, commercial or not;
- an alcohol concentration of 0.08 or more in a noncommercial vehicle; and
- an alcohol concentration of 0.04 or more in a commercial motor vehicle.
The key point for many drivers is the second item. A DUI in your own pickup on a Saturday night counts. The CDL consequences follow the driver, not the vehicle.
How Long a CDL Disqualification Lasts
Under MCA § 61-8-802(1), a first major offense suspends the CDL for 1 year. If the offense happened while operating a commercial motor vehicle transporting placardable hazardous materials, the suspension is 3 years. A second major offense from a separate incident brings a lifetime suspension, subject to reinstatement after a minimum of 10 years. The table below brings these rules together.
| Event | CDL consequence | Source |
|---|---|---|
| First major offense | CDL suspended 1 year | MCA § 61-8-802(1) |
| First major offense while hauling placardable hazardous materials | CDL suspended 3 years | MCA § 61-8-802(1) |
| Second major offense (separate incident) | Life, with reinstatement possible after a minimum of 10 years | MCA § 61-8-802(1) |
| Administrative 0.04 in a CMV, first violation | 1 year (3 years if hazmat), no restricted CDL | MCA § 61-8-805 |
| Administrative 0.04 in a CMV, second violation | Life, with reinstatement possible after 10 years | MCA § 61-8-805 |
| Test refusal, first / second or later | 1 year / life, with reinstatement possible after 10 years | MCA § 61-8-1032(4)(b) |
The Administrative 0.04 Rule and Out-of-Service Orders
Separate from the criminal case, MCA § 61-8-805 sets administrative consequences for commercial drivers. An alcohol concentration of 0.04 or more in a commercial motor vehicle brings a 1-year CDL disqualification, or 3 years if hazardous materials were involved, with no restricted CDL. A second violation brings a lifetime disqualification with reinstatement possible after 10 years.
There is also a lower trigger. Under the same section, a commercial driver with a measured amount or detected presence of alcohol is placed out of service for 24 hours. That applies below 0.04, and it can have employment consequences of its own.
No Probationary License for Commercial Driving
Many drivers with an ordinary DUI can get a restricted probationary license during a suspension. Commercial driving is different. Montana law does not allow a probationary license to drive a commercial motor vehicle during a disqualification (MCA § 61-2-302(9)(b)). Whether a probationary license for a personal vehicle is possible is a separate question, covered on our license suspension and hearings page.
When a CDL Holder Refuses a Test
Refusal is treated harshly for commercial drivers. A first refusal suspends the CDL for 1 year. A second or later refusal suspends it for life, with reinstatement possible after 10 years (MCA § 61-8-1032(4)(b)). That runs alongside the ordinary refusal suspension of the driver's license, which has no probationary license (MCA § 61-8-1032(2)(f), (4)(a)). Our test refusal and implied consent page explains the refusal process and the 30-day petition.
Why a CDL DUI Cannot Be Deferred
Montana does not allow a court to defer imposition of sentence on any DUI (MCA § 61-8-1011(4)), and for a commercial driver the conviction carries a disqualification on top of the criminal sentence. There is no deferral route that avoids either.
That is why the defense of the charge itself matters so much. Depending on the facts, the questions I look at include whether the stop was lawful, whether the vehicle was a commercial motor vehicle at the time, how the breath or blood test was given and handled, and whether the officer followed the implied consent procedure. If the stop included field sobriety testing, our field sobriety tests page explains how those tests are supposed to be given.
First Steps After a CDL DUI Arrest
The first days after an arrest shape what options remain later. A few practical steps can help:
- Keep every document the officer gave you, including any temporary permit and any notice of the right to a hearing. If you refused a test, the 30-day petition window under MCA § 61-8-1017 runs from that notice.
- Write down what happened while it is fresh: when you last had a drink or took any medication, which tests were offered, what the officer asked, and what you said.
- Note whether you were driving a commercial vehicle or your own, and whether you were hauling placardable hazardous materials. Those facts change which rules apply.
- Talk with a lawyer before you give any written or recorded statement about the arrest.
Protecting a Commercial Driving Career
A lifetime disqualification can follow a second major offense, so the first case is often the one that matters most. I work to understand what your job depends on, where the case and the disqualification each stand, and what options exist given your record. I am a member of the Montana Association of Criminal Defense Lawyers, and I aim to lay out those options clearly and early.
This page explains Montana law in general under the 2025 Montana Code and is not advice on a specific case.