Montana now has a number for certain drugs the way it has 0.08 for alcohol. Under MCA § 61-8-1002(1)(f), a person commits DUI by driving or being in actual physical control of a vehicle with a listed substance in their blood at or above a set level, without a valid prescription. The State does not have to show the person drove badly or seemed impaired. This page sets out the list exactly and explains the limits on it. It is part of our Montana DUI Guide.
The List, as Printed in MCA § 61-8-1002(1)(f)
The statute gives each level in blood nanograms per milliliter. A nanogram is a billionth of a gram.
| Subsection | Prohibited substance | Blood ng/mL |
|---|---|---|
| (i) | Amphetamine | 20 |
| (ii) | Cocaine | 20 |
| (iii) | Cocaine metabolite | 20 |
| (iv) | Heroin | 1 |
| (v)(A) | Heroin metabolite: morphine | 20 |
| (v)(B) | Heroin metabolite: 6-monoacetyl morphine | 1 |
| (vi) | Lysergic acid diethylamide (LSD) | 0.1 |
| (vii) | Methamphetamine | 20 |
| (viii) | Phencyclidine (PCP) | 5 |
| (ix) | Fentanyl | 0.5 |
The offense is committed at a level "equal to or greater than" the figure shown. The statute names "cocaine metabolite" without identifying a particular compound, and it lists morphine and 6-monoacetyl morphine under the heading of heroin metabolites.
What the Statute Requires the State to Prove
Reading subsection (1)(f) word by word, a per se drug charge has these parts:
- The person drove or was in actual physical control of a noncommercial or commercial motor vehicle.
- It happened "on the ways of this state open to the public."
- The person had a listed substance in their body at or above its level, "as shown by analysis of the person's blood."
- The person was "without a valid prescription."
Diminished driving ability is not on that list. That is what "per se" means, and it is the main difference from an impairment charge. Our page on per se and impairment DUI compares the two.
The Valid Prescription Wording
The words "without a valid prescription" are part of the offense itself. A person who holds a valid prescription for the substance found in their blood is not covered by subsection (1)(f), whatever the number.
Two cautions. First, the definitions section for the DUI laws, MCA § 61-8-1001, does not define "valid prescription." The statute does not say how an old prescription, a prescription from another state, or a dose above the prescribed amount is treated. Second, the wording does nothing for an impairment charge under § 61-8-1002(1)(a), which covers "any drug" whether prescribed or not.
The morphine line deserves a note. Morphine is listed as a heroin metabolite, but it is also a prescription pain medication, and NHTSA's Drugs and Human Performance Fact Sheets (2024) state that codeine is metabolized to morphine. A morphine result does not by itself say which drug a person took. See opioids and pain medication.
What Is Not on the List
The list is short. It does not include oxycodone, hydrocodone, methadone, or tramadol. It does not include alprazolam, diazepam, clonazepam, or any other benzodiazepine. It does not include zolpidem or other sleep medications, methylphenidate, muscle relaxants, antihistamines, or kratom.
That does not make driving on those substances lawful. Any substance that can impair a person's ability to operate a vehicle safely is a "drug" under MCA § 61-8-1001(7), and an impairment charge can rest on it. The difference is the proof: a positive test alone is not enough for an impairment conviction, and the State needs other competent evidence that the person was under the influence (MCA § 61-8-1018(1)(a)).
How THC Is Treated Differently
Marijuana is not in subsection (1)(f). It has its own subsections, (1)(d) and (1)(e), and the wording differs in ways that matter.
| Point | THC, § 61-8-1002(1)(d) and (e) | Listed drugs, § 61-8-1002(1)(f) |
|---|---|---|
| Substance | Tetrahydrocannabinol, excluding inactive metabolites | The ten listed substances |
| Level | 5 ng/mL or more (any amount under 21) | The level in the table above, or more |
| Sample | Blood or other bodily substance | Blood |
| Prescription wording | None in the text | Applies only "without a valid prescription" |
| Where | "Within this state" | "On the ways of this state open to the public" |
Because the THC subsection has no prescription wording, a medical marijuana card does not take a driver out of it.
Penalties and Aggravated DUI
A conviction under subsection (1)(f) is sentenced under MCA § 61-8-1007(2)(a), the same provision that covers the 0.08 and THC offenses. A first violation carries up to 6 months in jail and a fine of $600 to $1,000, with no minimum jail term. A second carries at least 5 days. A first impairment conviction, by contrast, carries at least 24 consecutive hours.
The definition of aggravated DUI in MCA § 61-8-1001(1) includes a violation of subsection (1)(f). A listed-drug offense committed while a license is suspended for a prior DUI, for example, can be charged as aggravated DUI.
Where These Cases Are Contested
A per se drug case depends on a blood sample and a laboratory report. The sample has to be drawn by a person qualified under MCA § 61-8-1019(1) and analyzed in a laboratory operated or certified by the Department of Justice, or one exempt from certification (MCA § 61-8-1018(1)(b)). Whether the stop and the request for blood were lawful, whether a prescription existed, and what the laboratory measured are the usual questions. Our guide to challenging a blood test goes through them.
This page explains Montana law in general as of the 2025 Montana Code Annotated. It is not legal or medical advice. Do not stop or change a prescribed medication without talking to your prescriber.