A drug recognition expert, or DRE, is an officer trained to evaluate a person suspected of drug-impaired driving through a fixed 12-step examination and then give an opinion about whether the person is impaired and by what category of drug. In a Montana DUI case that opinion is expert testimony, and it is often what the State uses to connect a lab result to impairment. This page explains the evaluation and how the evidence rules apply to it. It is part of our Montana DUI Guide.
What a DRE Is
The Drug Evaluation and Classification Program is run by the International Association of Chiefs of Police (IACP) with the National Highway Traffic Safety Administration (NHTSA). The IACP describes a DRE as someone "skilled in detecting and identifying persons under the influence of drugs and in identifying the category or categories of drugs causing the impairment."
According to the IACP, a DRE forms an opinion on three questions:
- Is the person impaired, and if so, able to operate a vehicle safely?
- Is the impairment due to an injury, illness, or other medical complication, or is it drug-related?
- If drugs, which category or combination of categories is the most likely source?
When a DRE Is Called
The first step of the protocol explains the trigger. The arresting officer reviews the breath test result and decides whether the person's apparent impairment is consistent with it. "If the impairment is not explained by the BrAC, the officer requests a DRE evaluation."
The IACP says the evaluation is "not normally done at roadside and is typically a post-arrest procedure," conducted in a controlled environment such as a station or intake center, and that it "takes approximately one hour to complete." A DRE is not involved in every drug DUI case. When there is no evaluation, the State relies on the arresting officer's observations and the field sobriety tests.
The 12 Steps
| Step | What happens (per the IACP) |
|---|---|
| 1. Breath alcohol test | The arresting officer compares the breath result with the apparent impairment. If the result does not explain it, a DRE is requested. |
| 2. Interview of the arresting officer | The DRE reviews the breath result and asks about the person's behavior, appearance, and driving. |
| 3. Preliminary examination and first pulse | Standard health questions, a check of pupil size and eye tracking, a first look for nystagmus, and a pulse. If a medical condition is suspected, the DRE is to seek medical help. |
| 4. Eye examination | Horizontal gaze nystagmus, vertical gaze nystagmus, and lack of convergence. |
| 5. Divided attention tests | Modified Romberg Balance, walk-and-turn, one-leg stand, and finger to nose. |
| 6. Vital signs and second pulse | Blood pressure, temperature, and pulse. |
| 7. Dark room examinations | Pupil size estimated under three lighting conditions with a pupilometer. |
| 8. Examination for muscle tone | Whether the muscles are rigid or flaccid. |
| 9. Injection sites and third pulse | A check for injection sites and a final pulse. |
| 10. Statements and other observations | Miranda warnings, if not already given, and questions about drug use. |
| 11. Analysis and opinion | The DRE's opinion on whether the person is impaired and which category or categories of drugs may have contributed. |
| 12. Toxicological examination | A chemical test to support the opinion. |
Two features of the sequence deserve attention. The opinion in step 11 is formed before the laboratory result in step 12 comes back. And step 3 includes a medical screen: if the DRE believes the person may have a significant medical condition, the protocol says to seek medical assistance immediately.
Step 5 uses two of the standardized roadside tests, covered in the walk-and-turn and the one-leg stand, plus two that are not part of the roadside battery, discussed in non-standard field tests.
Why DRE Evidence Matters in Montana
Montana has two kinds of drug DUI. A per se charge rests on a blood level, such as 5 ng/mL of THC or one of the listed drug limits (MCA § 61-8-1002(1)(d), (f)). An impairment charge under § 61-8-1002(1)(a) rests on proof that a drug diminished the person's ability to drive safely.
For the impairment charge, the Legislature added a safeguard: "A positive test result does not, in itself, prove that the person was under the influence of a drug," and a person may not be convicted based on the presence of a drug "unless some other competent evidence exists that tends to establish that the person was under the influence" (MCA § 61-8-1018(1)(a)). A DRE evaluation is one of the main ways the State tries to supply that other evidence. See prescription and drug DUI and our THC DUI page.
How Montana's Evidence Rules Treat a DRE
Three sources apply.
- The DUI evidence statute. A report of "a physical, psychomotor, or physiological assessment" is admissible if it was made by a person trained by the Department of Justice or with training the Department recognizes (MCA § 61-8-1018(1)(c)).
- Rule 702. Expert testimony is allowed when specialized knowledge will assist the trier of fact and the witness is qualified by knowledge, skill, experience, training, or education. The Montana Supreme Court quoted and applied that rule to roadside testing in Hulse v. State, 1998 MT 108, ¶ 47.
- The eye test cases. In State v. Bollman, 2012 MT 49, the Court listed certification as a drug recognition expert among the qualifications it has found significant in deciding whether an officer may testify about the science behind the eye test (¶ 28). The trooper there was a certified DRE with additional training, and the Court upheld his qualification (¶¶ 29 to 30).
We did not find a Montana Supreme Court decision that rules directly on whether, and with what limits, a DRE may give an opinion that a person was impaired by a particular drug category. Without one, admissibility is decided by the trial judge under Rule 702, case by case, and practice varies by court. We say that plainly because some websites describe the question as settled in one direction or the other.
Where a DRE Evaluation Can Be Tested
- Completeness. The protocol is described as standardized, meaning done the same way every time. Skipped or reordered steps are departures from it.
- Medical alternatives. Step 3 exists to catch illness and injury. NHTSA's field sobriety manual separately reminds officers that some medical conditions have symptoms in common with alcohol influence.
- The match. The DRE names a drug category before the lab reports. If the toxicology report finds something different, or nothing, that is significant.
- Qualifications. Training records and certification status can be requested like any other expert's.
- Statements. Step 10 involves questioning about drug use. Whether warnings were given and whether answers were voluntary are separate legal questions.
- Recording. If the evaluation was recorded, the video can be compared with the evaluation form.
If a DRE Evaluated You
Write down what you remember: where it happened, how long it took, what you were asked, and what you said about medication or medical conditions. Gather your prescription records. The listed drug limits in MCA § 61-8-1002(1)(f) apply only to a person without a valid prescription. The impairment offense in § 61-8-1002(1)(a) has no such wording.
A DRE opinion is one person's structured judgment. It is neither meaningless nor conclusive, and the evaluation form shows the reasoning behind it.
This page explains Montana law in general as of the 2025 Montana Code Annotated and describes the DRE protocol as published by the International Association of Chiefs of Police. It is not legal advice about your specific case.