If you have been pulled over for suspected impaired driving in Minnesota, you may hear an officer mention a “DRE.” Those three letters can shape the outcome of a DWI case, and for parents in the middle of a divorce, they can matter in family court too. Understanding what a Drug Recognition Expert is and how a DRE evaluation works helps Minnesotans know what they are facing.
What Is a Drug Recognition Expert?
A Drug Recognition Expert (DRE), sometimes called a Drug Recognition Evaluator, is a law enforcement officer trained to determine whether a driver is impaired by drugs other than, or in addition to, alcohol, and to identify the category of drug likely responsible. DREs are certified through the Drug Evaluation and Classification Program (DECP), coordinated by the International Association of Chiefs of Police (IACP) with support from the National Highway Traffic Safety Administration (NHTSA).
The program began with the Los Angeles Police Department in the 1970s, after officers noticed that many drivers arrested for impairment had little or no alcohol in their systems. NHTSA and the IACP expanded it nationally beginning in the late 1980s, and today every state participates.
Minnesota’s DRE Program
In Minnesota, the program is administered by the Minnesota State Patrol and the Department of Public Safety’s Office of Traffic Safety. The state now has more than 300 certified DREs representing roughly 145 agencies.
Certification is rigorous. Candidates complete a preliminary school and a 56-hour main school covering pharmacology, physiology, and drug categories, then must perform a series of supervised field evaluations confirmed by laboratory testing. To stay certified, DREs must complete instructor-witnessed evaluations each year along with continuing education.
The 12-Step DRE Evaluation
A DRE evaluation follows a standardized 12-step protocol, usually conducted at a police station after arrest:
- Breath alcohol test to rule out alcohol as the sole cause of impairment.
- Interview of the arresting officer about driving and behavior.
- Preliminary examination and first pulse to screen for medical conditions.
- Eye examinations, including horizontal and vertical gaze nystagmus and lack of convergence.
- Divided attention tests such as the Walk and Turn, One Leg Stand, Modified Romberg Balance, and Finger to Nose.
- Vital signs and second pulse, including blood pressure and temperature.
- Dark room examination of pupil size under different lighting conditions.
- Muscle tone examination for rigidity or flaccidity.
- Injection site check and third pulse.
- Subject’s statements and observations, often after a Miranda advisory.
- Evaluator’s opinion on impairment and drug category.
- Toxicological examination through a blood or urine sample.
DREs classify impairment into seven categories: central nervous system depressants, CNS stimulants, hallucinogens, dissociative anesthetics, narcotic analgesics, inhalants, and cannabis.
Minnesota Drugged Driving Law
Minnesota’s DWI statute, Minn. Stat. § 169A.20, makes it a crime to drive while under the influence of a controlled substance or hazardous substance. It also includes a zero-tolerance provision for driving with any amount of a Schedule I or II controlled substance in the body, but that provision specifically excludes marijuana and THC.
That exclusion became more significant when Minnesota legalized adult-use cannabis in August 2023. Unlike the 0.08 alcohol standard, there is no per se THC limit for driving, so prosecutors must prove actual impairment. That is exactly where DRE evaluations carry the most weight. Minnesota’s implied consent law also allows officers to seek blood or urine testing, though a search warrant is generally required.
The state has also piloted roadside oral fluid screening devices administered by DREs. Those screening results are not admissible in court, and as of this writing the Legislature has not authorized roadside oral fluid testing beyond the pilot stage.
How Minnesota Courts Treat DRE Testimony
The Minnesota Supreme Court held that the DRE protocol is not a novel scientific technique subject to heightened scrutiny, describing it instead as a structured checklist a trained officer follows before offering an opinion. The court allows that opinion into evidence with proper foundation but cautions that the officer should not be labeled an “expert” in front of the jury, leaving the weight of the testimony to jurors.
Why a DRE Matters in Divorce and Custody Cases
A drug-related DWI arrest rarely stays confined to the criminal courtroom. Minnesota custody and parenting time decisions are governed by the best-interest factors, which include any chemical health issue of a parent that affects a child’s safety or developmental needs.
A DRE report, DWI charge, or toxicology result can become evidence a judge, custody evaluator, or guardian ad litem considers. Courts may order a chemical use assessment, parenting time can be restricted or supervised when it is likely to endanger a child’s physical or emotional health. A single incident does not automatically cost a parent custody; the question is whether substance use affects the ability to parent safely. Completing an assessment or treatment can help a parent move toward expanded parenting time.
Limitations of DRE Evaluations
DRE evaluations are not infallible. The protocol relies heavily on subjective observations, including pupil size and muscle tone, and confirmation bias can influence conclusions. Toxicology confirms the presence of a drug, not impairment at the time of driving, which is especially significant for cannabis, since THC can remain detectable long after its effects fade. Independent researchers have also questioned the methodology behind the program’s original validation studies.
Why an Experienced Minnesota DWI Attorney Matters
Because a DRE evaluation combines subjective observation, physiological measurements, and chemical testing, there are many points where the process can go wrong: improperly administered tests, lapsed certification, a warrant that was never obtained, or a toxicology result that does not match the officer’s opinion.
An experienced Minnesota DWI attorney knows how to scrutinize each of the 12 steps, and challenge the foundation for DRE testimony. When a DRE is involved, the stakes reach well beyond a traffic charge, and skilled legal guidance can make a meaningful difference.
