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Drug Recognition Expert Evaluations

When a police officer suspects that a person is impaired by alcohol and or drugs, he or she will conduct a series of tests to determine if there are probable grounds to conduct further testing. A police officer may use a divided attention test battery known as the Standardized Field Sobriety Tests or SFSTs. This series of tests has undergone a number of field validation studies in the United States and Canada that have shown it produces accurate indicators of a blood alcohol level of 80mg% (.08) or greater. In addition, the tests do show impairment that can be caused by other things such as prescription or illicit drugs. The SFST test battery consists of examining eyes, the Walk and Turn test and One Leg Stand test.

The evaluation of a suspected drug impaired driver is conducted by an evaluator who is accredited by the International Association of Chiefs of Police, through the RCMP. The Drug Recognition Expert (DRE) uses a 12-step procedure in performing the evaluation. These steps are:

  1. Breath test to rule out alcohol as the primary cause of impairment
  2. Interview of the arresting officer
  3. Preliminary examination (includes the first of three pulse checks)
  4. Eye examinations (Horizontal Gaze Nystagmus, Vertical Gaze Nystagmus and the ability of the eyes to converge)
    A man follows a pen with his eyes A man follows a pen with his eyes
  5. Divided attention tests (SFSTs plus finger to nose and Modified Romberg balance test)
    A man walking heel-to-toe A man with his eyes closed touches his nose with his index finger
  6. Clinical indicators examinations (blood pressure, temperature, second pulse)
    Close-up of an arm getting blood pressure taken
  7. Darkroom examination of pupil sizes (also includes examination of nasal and oral cavities)
    A police officer checks a man's pupil size
A police officer checks a man's pupil size
  8. Muscle tone examinations
  9. Search for and examination of injection sites
    A police officer uses a magnifying glass with a light to check for injection sites
  10. Statements and interview of the suspect
  11. Opinion of the DRE
    Based on the totality of the evaluation, the DRE forms an opinion as to whether or not the subject is impaired. If the DRE determines that the subject is impaired, the DRE will indicate what category or categories of drugs may have contributed to the subject's impairment. The DRE bases these conclusions on his training and experience and the DRE Drug Symptomatology Matrix. While DREs use the drug matrix, they also rely heavily on their general training and experience.
  12. Toxicological sample (urine and oral fluid or blood)
    After the evaluation, the toxicological sample is sent to a forensic laboratory for analyses to confirm or refute the findings of the evaluator. The mere presence of a drug in the sample does not constitute sufficient evidence to charge a person as being impaired by a drug. The evaluation must show impairment, signs and symptoms consistent with one or more drug categories, and the evaluator's findings must be supported by the toxicology.