Drug Recognition Experts

A Drug Recognition Expert (DRE) is a law enforcement officer who administers tests on suspected impaired drivers to attempt to determine whether the individual is impaired and if so, to categorize the type of impairing substance. Law enforcement officers become DREs by completing a three phase course. DREs are trained to follow a 12-step protocol.

DRE testimony is used to prosecute cases of suspected drugged driving because of the limitations of toxicology testing. Blood tests may detect the presence of a substance, but the tests used do not measure the quantity of substance ingested or whether amount of the substance is sufficient to cause impairment in an individual. Thus, the testimony of a DRE is often needed to show impairment.

Challenging Admissibility

Rule 702(a1) was enacted in 2006 by the General Assembly of North Carolina and addresses the admissibility of testimony by a DHHS-certified DRE. Rule 702(a1) requires proper foundation and that the witness be qualified under the standard requirements for expert testimony, as set forth in Rule 702(a).

In State v. Moore (2025), the Court of Appeals held that the Rule 702(a)(3) does apply to DRE testimony and thus, witness testimony must apply the certification principles and methods reliably to the facts of the case. In cases where one or more step of the 12-step DRE protocol was not reliably administered or the DRE did not personally examine the defendant, defenders should be objecting to this testimony under State v. Moore and Rule 702(a)(3). Take a look at this 2025 School of Government post on the topic.

Challenging a Drug Recognition Expert’s Qualifications

When challenging a DRE’s qualifications, counsel should consider these areas:

• Does the DRE have medical training that renders him qualified to evaluate a suspect’s physiological symptoms?
• The DRE protocol requires the DRE to make a medical diagnosis during the examination by ruling out medical conditions. What training does the DRE have regarding distinguishing effects of drugs from other medical conditions?
• How well did the DRE do in the training course? What continuing education has he had? International Association of Chiefs of Police standards require recertification every two years.
• On the DRE certification exam, an officer can identify impairment by multiple substances and if the subject is impaired by any of the substances identified, the answer is deemed correct. How many substances did the officer incorrectly identify on the qualification test?
• What is the DRE’s track record? DREs are required to maintain a “Progress Log” and a “Rolling Log” of all drug influence evaluations.
• Did the DRE deviate from the protocol? The DRE protocol requires the measurement of the suspect’s blood pressure and temperature twice and measurement of pulse three times; dark room examinations of the suspect’s eyes; examination of skeletal muscle tone; a toxicological examination; and other examinations. The protocol requires that an opinion be based on a complete administration of all 12 steps.
• What is the minimum number of indicators that a DRE needs to reach an opinion of impairment? Does the DRE believe there is a standard set by the DEC program regarding minimum number of indicators or does each DRE determine his/her own minimum?
• Does a determination that the defendant was affected by drugs mean that the defendant’s driving was impaired?
• The DRE protocol is considered a “diagnostic examination” in which the DRE to “evaluates and assesses the person’s appearance and behavior;…measures and records vital signs and makes precise observations of ther person’s automatic responses and reactions; [and]…administers carefully designed psychophysical tests to evaluate the person’s judgment, information processing ability, coordination and various other characteristics.” If the DRE does not personally conduct the examination, but instead relies on another officer’s notes, is it possible to complete these evaluations?

Challenging the Reliability of the DRE Protocol

Law enforcement agencies have attempted to demonstrate the reliability of the DRE protocol through research; however, these studies indicate a high rate false positives and the misidentification of impairing substances. Attorneys should consider whether these studies were conducted using appropriate research protocols including use of a double-blind research design, use of a contol group, use of relevant dosages of impairing substances, use of appropriate statistical analysis to assess the relevance of the results, and whether the research was peer reviewed.

• The Heishman Study I, Heishman Study II, the Shinar and Schectman Study are peer reviewed and published studies on the subject of the DRE protocol. These studies indicate high rates of misidentification of substances and false positives.
• Drug Recognition Expert (DRE) Validation Study – a 1994 study by Eugene Adler of the Arizona Department of Public Safety and Marcelline Burns of the Southern California Research Institute. The study suggests that lab tests failed to find any drug present in 16.4% of case samples where DREs identified drug impairment (p. xi). This figure does not reflect the number of cases where DREs determined impairment and the suspect had a controlled substance present in his blood, but not a sufficient amount to cause impairment.
• Field Evaluation of the Los Angeles Police Department Drug Detection Procedure – a 1986 study by the US Department of Transportation on the rate of correct impairment identification by DREs. In 49% of the cases, the DREs correctly identified every controlled substance found in a toxicology screening (p. 16). This study did not measure the number of cases where DREs determined impairment and the suspect had a controlled substance present in his blood, but not a sufficient amount to cause impairment.
• See State v. Sampson, 167 Ore. App. 489 (2000) for a discussion of research regarding the error rate of DRE evaluations.