Legislative Background: reforms to the Transportation Provisions of the Criminal Code (Bill C-46)

Annex 2 – Drugs and Driving Committee report on drug per se limits

Executive Summary

  • Establishing a drug per se limit does not imply all drivers below this limit are not impaired and all drivers above this limit are impaired.
  • Impairment can be defined as a decreased ability to perform a certain task; this differs from intoxication which can be described as the observable signs of drug use.
  • The primary psychoactive compound in cannabis products is tetrahydrocannabinol (THC).
  • THC impairs the ability to operate a motor vehicle.
  • THC is the most frequently encountered drug in Canadian drivers, after alcohol.
  • THC and alcohol are frequently detected in combination in drivers.
  • Although the scientific literature varies, several well-controlled studies with sufficient discriminating power have demonstrated an increased crash risk in THC-positive drivers. Risks were increased for fatal collisions and with elevated THC concentrations.
  • Available evidence suggests significantly increased risks for drivers positive for alcohol and THC in combination.
  • Unlike alcohol, the effects of THC do not correlate well with THC blood concentrations.
  • Impairment due to THC is related to the amount, the route of administration, the time elapsed since use, and inter-individual variability.
  • Existing per se limits for THC vary widely between jurisdictions.
  • The THC per se limits considered by this committee are 5 ng/mL and 2 ng/mL in blood.
  • The 5 ng/mL THC per se limit is based upon impairment considerations, while the 2 ng/mL THC per se limit is based upon public safety considerations.
  • This committee recommends the use of distinct but corresponding per se limits for plasma.
  • This committee recommends a combined offence of 50 mg of alcohol in 100 mL of blood when detected in combination with THC at a concentration less than the limit for the THC alone offence.
  • Minimizing time delays in sample collection is critical to implementation of an effective THC per se limit.
  • Consideration of THC per se limits is complicated by the potential for prolonged THC blood concentrations in chronic users although there is evidence of residual impairment in this population.
  • The potential for passive exposure to THC resulting in concentrations at or above a per se limit is not a practical concern in the context of the conditions that would be required, the levels discussed and the inevitable time delay to sample collection.
  • Cocaine is a central nervous system stimulant which impairs the ability to operate a motor vehicle. Cocaine is susceptible to degradation in the body and in a collection tube; therefore, timely collection, preservative and proper storage conditions, and timely analysis are important. This committee recommends a cocaine per se limit of 30 ng/mL in the blood. No limit is recommended for benzoylecgonine, the inactive breakdown product of cocaine.
  • Gammahydroxybutyrate (GHB) is a drug which demonstrates central nervous system depressant activity in a dose dependent manner. GHB impairs the ability to operate a motor vehicle. GHB is also a compound that occurs naturally in the body at low levels, and as such, the per se limit must reflect a concentration above endogenous levels. This committee recommends a GHB per se level of 10 mg/L in the blood.
  • Heroin is an opioid analgesic which has central nervous system depressant properties. Heroin impairs the ability to operate a motor vehicle. Given the extremely short time frame for heroin detection in the body due to the rapid metabolism of heroin to its active metabolite, 6-monoacetylmorphine (6-MAM), this committee recommends zero tolerance for 6-MAM detection in the blood.
  • Ketamine is a dissociative anaesthetic which impairs the ability to operate a motor vehicle. This committee recommends zero tolerance for ketamine detection in the blood.
  • Lysergic Acid Diethylamide (LSD) is a potent hallucinogen which impairs the ability to operate a motor vehicle. This committee recommends zero tolerance for LSD detection in the blood. LSD is susceptible to degradation in a collection tube as it is light and heat labile; therefore, proper storage conditions and timely analysis are important.
  • Methamphetamine is a central nervous system stimulant which impairs the ability to operate a motor vehicle. This committee recommends a methamphetamine per se limit of 50 ng/mL in the blood.
  • Phencyclidine (PCP) is a dissociative anaesthetic which impairs the ability to operate a motor vehicle. This committee recommends zero tolerance for PCP detection in the blood.
  • Psilocybin is the compound present in ‘magic’ mushrooms which are used for hallucinogenic purposes; psilocin is the primary psychoactive metabolite of psilocybin. Psilocybin/psilocin impairs the ability to operate a motor vehicle. This committee recommends zero tolerance for psilocybin and/or psilocin in the blood.
  • Any drug recommended for zero tolerance in a blood sample is also recommended for zero tolerance in a serum or plasma sample.
  • Since zero tolerance will be related to the limits of the methodology employed, this committee recommends that the provincial and federal government forensic laboratory systems develop a common limit of detection for the aforementioned drugs so as to ensure the Criminal Code offence will not vary between jurisdictions.
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