DUI in Glacier, Yellowstone, and on Federal Land in Montana

A DUI inside Glacier or Yellowstone is a federal case. It is charged under a National Park Service regulation, prosecuted by federal attorneys, and heard by a United States magistrate judge. The regulation looks a lot like Montana's DUI law, but the standard, the testing rules, and the court are different. This page explains those differences and what applies on other federal land. It is part of our Montana DUI Guide.

The Regulation: 36 CFR § 4.23

The rule prohibits operating or being in actual physical control of a motor vehicle while:

• under the influence of alcohol, a drug, or any combination, "to a degree that renders the operator incapable of safe operation"; or
• the alcohol concentration in the operator's blood or breath is 0.08 or more.

If state law sets "more restrictive limits of alcohol concentration," those limits supersede the 0.08 figure. The rule applies even if the operator was legally entitled to use the alcohol or drug, which covers prescription medication. And like Montana law, it reaches actual physical control, so a person can be charged without being seen driving.

A result under the limit does not end the case. The regulation says a lower result gives rise to no presumption that the operator is or is not under the influence, and other competent evidence can still be used (36 CFR § 4.23(d)).

State Law Fills the Gaps

Park traffic rules borrow from the state. "Unless specifically addressed by regulations in this chapter, traffic and the use of vehicles within a park area are governed by State law," and violating that state law is prohibited as a federal matter (36 CFR § 4.2). Impaired driving is specifically addressed by § 4.23, so that section controls the DUI charge itself. Other Montana traffic rules can come in through § 4.2 and be cited alongside it.

How a Park DUI Differs From a State DUI

One difference cuts in the driver's favor on paper: the federal penalty statute has no mandatory minimum jail term. Another cuts the other way: a refusal is not just a licensing problem but a separate violation.

Testing and Refusal in a Park

When an authorized person has probable cause to believe the operator has violated the rule, the operator "shall submit to one or more tests of the breath, saliva, or urine." Refusal is prohibited, and proof of refusal may be admissible (36 CFR § 4.23(c)(1), (2)).

Blood is handled separately. Absent exigent circumstances, an operator cannot ordinarily be required to give a blood sample without a search warrant, and the regulation directs the officer to get one (36 CFR § 4.23(c)(3)). Tests must use "accepted scientific methods and equipment of proven accuracy and reliability operated by personnel certified in its use," which gives the defense the same kinds of questions about the instrument and the operator that arise in a state case.

Federal Court: What to Expect

Because the maximum is 6 months, a park DUI is a "petty offense" under federal law (18 U.S.C. § 19). Magistrate judges try misdemeanors, and a person charged with a petty offense does not have the option of electing trial before a district judge (18 U.S.C. § 3401). A federal sentence can include probation, which for a misdemeanor can run up to 5 years (18 U.S.C. § 3561(c)(2)).

Which federal court depends on the park:

• Glacier National Park is under the sole and exclusive jurisdiction of the United States (16 U.S.C. § 163) and lies in the District of Montana.
• Yellowstone National Park is also under exclusive federal jurisdiction (16 U.S.C. § 24). By statute, Wyoming and the portions of Yellowstone in Montana and Idaho form one judicial district (28 U.S.C. § 131). An arrest near West Yellowstone or Gardiner, but inside the park boundary, is a District of Wyoming case.

Lawyers must be admitted to the federal court where the case is filed. Ask about that when you call.

Open Containers, Snowmobiles, and Boats

Parks have their own open container rule. Carrying or storing an open container of alcohol within a motor vehicle in a park area is prohibited, with exceptions for the trunk or a similar storage area, the living quarters of a motor home or camper, and a vehicle parked at an authorized campsite where the occupants are camping (36 CFR § 4.14). Each person in the vehicle is responsible for what they carry.

The park DUI rule also applies to snowmobiles (36 CFR § 2.18), and a parallel rule covers vessels (36 CFR § 3.10).

National Forests, BLM Land, and Wildlife Refuges

Most federal land in Montana is not national park. The rules differ by agency:

• National forest roads. Traffic on National Forest System roads "is subject to State traffic laws where applicable" (36 CFR § 212.5(a)(1)). A DUI on a forest road is commonly a state charge. Off the roads, operating a vehicle under the influence in violation of state law is a federal violation with a 6-month maximum (36 CFR §§ 261.15(e), 261.1b).
• BLM land. No person may operate an off-road vehicle on public lands while under the influence of alcohol, narcotics, or dangerous drugs (43 CFR § 8341.1(f)(3)).
• National wildlife refuges. "No operator of a vehicle shall be under the influence of intoxicating beverages or controlled substances" (50 CFR § 27.31(b)).

On a public highway that passes through national forest or BLM land, the usual result is a stop by a state trooper or county deputy and a case in state court, under the rules in our first-offense DUI page. Military bases and other federal property are covered in DUI on military or federal property, and visitors from other states should also read our page for out-of-state drivers.

This page explains federal and Montana law in general as of October 2026. It is not legal advice about your specific case.