Drug Evaluation and Classification Program

Definition: The Drug Recognition Expert (DRE) procedure is a 12-step standardized and systematic process to determine if a motorist is driving under the influence of drugs (DUID). Police officers with specialized training, known as Drug Recognition Experts, perform an evaluation procedure that can distinguish individuals under the influence of alcohol, other drugs, combinations of alcohol and other drugs, and injury/illness. Developed in the 1970’s, the process is scientifically validated and a DRE’s evaluation may be admissible as evidence in court.

Executive Summary: The DRE process is a method for collecting evidence, with safeguards to ensure accuracy of the DRE’s opinion and conclusions. DREs are trained to follow a 12-step evaluation process consisting of interviews, preliminary breath testing, SFST’s, examination of the eyes and vital signs, and submission of a toxicological sample. The DRE evaluation is standardized and systematic and based upon observable signs and symptoms known to be reliable indicators of drug impairment. The DRE’s final opinion is based on the sum of information from the evaluation, not just one element. According to researchers, DRE evaluations of drug impairment are corroborated by toxicology results in over 85% of cases.

More Details: The International Association of Chiefs of Police (IACP) define the 12 steps of the drugs evaluation process as follows (see The Drug Evaluation and Classification Program by IACP):

  1. Breath Alcohol Test— The arresting officer reviews the subject’s breath alcohol concentration (BrAC) test results and determines whether the subject’s apparent impairment is consistent with the subject’s BrAC. If the subject’s impairment is consistent with the BrAC, the officer will not call a DRE. If the impairment is not explained by the BrAC, the officer requests a DRE evaluation.
  2. Interview of the Arresting Officer— The DRE commences his or her investigation by reviewing the BrAC test results and discussing the circumstances of the arrest with the arresting officer(s).The DRE asks about the subject’s behavior, appearance, and driving pattern. The DRE also asks whether the subject made any statements and whether the arresting officer(s) found any other relevant evidence, like a small pipe or a baggie.
  3. Preliminary Examination and First Pulse— During this step the DRE will perform a preliminary examination checking for any evidence of a medical complication that would warrant terminating the evaluation and requesting medical assistance. The suspect is asked a series of questions, and the DRE conducts a series of eye examinations that assists in making the decision whether the suspect is under the influence of alcohol and/or drugs or if the impairment may be medically related. If drug impairment is suspected, the DRE proceeds with the evaluation.
  4. Eye Examination— The DRE examines the subject for horizontal gaze nystagmus (HGN), vertical gaze nystagmus (VGN) and a lack of ocular convergence. A subject lacks convergence if his or her eyes are unable to converge toward the bridge of his nose when a stimulus is moved in. Depressants, inhalants, and dissociative anesthetics, the so-called DIP drugs, may cause HGN. In addition, the DIP drugs may cause VGN when taken in higher doses. The DID drugs, as well as cannabis (marijuana), may also cause a lack of convergence.
  5. Divided Attention Psychophysical Tests— The DRE administers four psychophysical tests: the Modified Romberg Balance, the Walk and Turn, the One Leg Stand, and the Finger to Nose tests. The DRE can accurately determine whether a subject’s psychomotor and/or divided attention skills are impaired by administering these tests.
  6. Vital Signs and Second Pulse— The DRE takes the subject’s blood pressure, temperature and pulse. Some drug categories may elevate the vital signs. Others may lower them. Vital signs thus provide much valuable evidence of the presence and influence of a variety of drugs.
  7. Dark Room Examinations— The DRE estimates the subject’s pupil sizes under three different lighting conditions with a pupilometer to determine whether the pupils are dilated, constricted, or normal. Some drugs increase pupil size. Others may decrease pupil size. The DRE also checks for the eyes’ reaction to light. Certain drugs may slow the eyes’ reaction to light. Finally, the DRE examines the subject’s nasal and oral cavities for signs of ingestion.
  8. Examination for Muscle Tone— The DRE examines the subject’s skeletal muscle tone. Certain categories of drugs may cause the muscles to become rigid. Other categories may cause the muscles to become very loose and flaccid.
  9. Check for Injection Sites and Third Pulse— The DRE examines the subject for injection sites, which may indicate recent use of certain types of drugs. The DRE also takes the subject’s pulse for the third and final time.
  10. Subject’s Statements and Other Observations—The DRE typically reads Miranda, if he or she has not done so previously, and asks the subject a series of questions regarding the subject’s drug use.
  11. Analysis and Opinions of the Evaluator— Based on the totality of the evaluation, the DRE forms an opinion as to whether the subject is impaired. If the DRE determines that the subject is impaired, the DRE indicates what category or categories of drugs may have contributed to the subject’s impairment. The DRE bases these conclusions on his or her training and experience, drug symptomatology matrix, and information observed during the 12-step evaluation.
  12. Toxicological Examination— The DRE requests a urine, blood and/or saliva sample from the subject and sends the sample to the toxicology lab for analysis.

Nothing in the DRE procedure is new or novel. The procedures in the DRE evaluation are modified versions of tests physicians have used for decades to assess drug impairment. The relationship between vital signs and foreign substances is well documented in medical literature. Physicians have recognized HGN and VGN as an indicator of substance impairment since the early 1900’s. Alcohol and other drugs are known to impair motor skills, which physicians have assessed using a battery of psychomotor tests. These procedures, all rooted in science, form the underlying framework of the 12 step drug evaluation process.

Admissibility in Court: DRE testimony has provided compelling evidentiary support for prosecutors in drugged driving cases. Defense attorneys in several states have challenged whether DRE officers should be allowed to testify as expert witnesses under Frye or Daubert standards. In Frye courts (Frye v. United States 293 F. 1013 ( D.C.. Cir 1923)), new evidence is admissible if it is generally accepted in the scientific community. In Daubert courts (Daubert v. Merrell Dow Pharmaceuticals, Inc. 509 U.S. 579 (1993)), new evidence is admissible if the court determines the underlying reasoning and methodology is scientifically valid. The DRE process is based on a compilation of accepted medical theories and practices. Decisions to admit DRE testimony as evidence has been overwhelmingly favorable in both types of court settings.

In Frye jurisdictions, every court that has considered the admissibility DRE testimony has ruled in favor of the DRE testimony except one, Maryland v. Squire32 Md. App. 307 (Md. Ct. Spec. App. 1976). In the ruling, the judge was concerned the DRE program had not gained general acceptance in the scientific community. According to the American Prosecutors Research Institute, the court’s decision was aberrant and inconsistent with the evidence; Frye applies to a method’s underlying theories and procedures, not to the resulting opinion testimony. In Daubert jurisdictions, every court that has considered the admissibility of DRE testimony has ruled in favor of it.


Suggested Audience: Enforcement, Prosecutors, Judges


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