Drug Recognition Evaluation (DRE)
A Drug Recognition Evaluation, or DRE, is a structured 12-step assessment performed by a specially trained Drug Recognition Expert officer to determine whether a driver is impaired by a drug and, if so, which drug category is responsible. DREs are authorized under section 320.28(2) of the Criminal Code. They are used where alcohol does not explain observed impairment or where drug impairment is suspected.
Mass Tsang's DUI lawyers handle drug-impaired driving files involving DRE evidence, with attention to the technical and Charter dimensions of the assessment. For more, see our blog post on cannabis-impaired driving laws.
The 12-step protocol
The DRE protocol includes: a breath alcohol test (to rule out or confirm alcohol involvement); an interview with the arresting officer; a preliminary examination including pulse; eye examinations (horizontal gaze nystagmus, vertical gaze nystagmus, lack of convergence); divided attention tests (Romberg balance, walk-and-turn, one-leg stand, finger-to-nose); vital signs assessment; dark-room examinations; muscle tone examination; injection-site examination; suspect's statements; and the officer's opinion. The protocol concludes with a toxicological sample (oral fluid, urine, or blood).
When DREs are demanded
Police can demand a DRE under section 320.28(2) where they have reasonable grounds to believe the driver was impaired by a drug or by a combination of alcohol and a drug. Failure to comply with a DRE demand is itself a criminal offence under section 320.15. The demand triggers Charter section 10 rights — the right to counsel must be implemented before the DRE proceeds.
How DRE evidence is used at trial
DRE officer opinions are admissible as opinion evidence under common-law principles (and, increasingly, under R v Bingley, 2017, which recognized DRE officers as having specialized training that allows them to give such opinions). The officer's opinion is one piece of evidence; the Crown typically also relies on the toxicology results, the arresting officer's observations, and standardized field sobriety test results.
Defence challenges
Common defence challenges to DRE evidence include: improper administration of the protocol (failure to complete all 12 steps, deviations from training); officer qualifications and currency of certification; reliability of the underlying eye examinations and divided attention tests (which have been criticized in some scientific literature); causal link between drug presence and observed impairment (drugs can remain in the system after impairment subsides); Charter issues with the underlying detention, demand, or right-to-counsel implementation; and statutory requirements regarding timing and procedure.
Related glossary terms
