What are Canada's DUID maximum per se limits for blood drug concentration?

The following is an excerpt from the Regulation defining Canada's BDC limits under the Criminal Code:

Summary offence

1 For the purpose of paragraph 253(3)(b) of the Criminal Code, the prescribed blood drug concentration for tetrahydrocannabinol (THC) is 2 ng of THC per mL of blood.

Hybrid offence — drugs

2 For the purpose of paragraph 253(3)(a) of the Criminal Code, the prescribed blood drug concentration for each drug set out in column 1 of the table to this section is set out in column 2.


1 Tetrahydrocannabinol (THC)

5 ng/mL of blood

2 Lysergic acid diethylamide (LSD)

Any detectable level

3 Psilocybin

Any detectable level

4 Psilocin

Any detectable level

5 Phencyclidine (PCP)

Any detectable level

6 6-Monoacetylmorphine

Any detectable level

7 Ketamine

Any detectable level

8 Cocaine

Any detectable level

9 Gamma hydroxybutyrate (GHB)

5 mg/L of blood

10 Methamphetamine

Any detectable level

Hybrid offence — combination of drugs and alcohol

3 For the purpose of paragraph 253(3)(c) of the Criminal Code, the prescribed blood alcohol concentration is 50 mg of alcohol per 100 mL of blood and the prescribed blood drug concentration for tetrahydrocannabinol (THC) is 2.5 ng of THC per mL of blood.

Please note the following commentary to the Regulation in the Gazette. The commentary effectively rules out operating a conveyance any time after consuming/using recreational or medical cannabis:

"It should be noted that THC is a more complex molecule than alcohol and the science is unable to provide general guidance to drivers about how much cannabis can be consumed before it is unsafe to drive or before the BDC levels enacted under the Regulation would be exceeded. It is equally challenging to provide general advice as to how long a driver should wait to drive after consuming cannabis. In this context, the safest approach for anyone who chooses to consume cannabis is to not mix their cannabis consumption with driving."

Please see the comments by the representatives from the Canadian Chiefs of Police and another expert who gave evidence to the Justice Committee that no one who uses mairijuana should drive anytime after consumption. 

Medical cannabis (including CBD oil) contains a small percentage of THC that will be detected by Approved Drug Screening Equipment such as the DrugTest 5000 and be found in a urine screening. The metabolite of that THC may be found much later  (perhaps many days) in an evidentiary urine test.

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Please note the comments in the Gazette (link above) respecting the rationale behind the establishment of these per se limits. Because "any detectable level" can be a very small concentration, it will be imperative that the forensic science methodology used to establish this trace, is reliable. The Courts will need to carefully consider police and lab continuity issues, whether or not the lab is accredited, whether or not standard operating procedures were followed, whether the substance may be acquired by the body naturally, second-hand, or environmentally, and whether the lab complied with good ISO 17025 laboratory practice. Screening equipment or methodologies, such as IA or ELISA should never be used for a non-screening forensic purpose. 

Please note that false positives are common in urine screening. An example is the detection of "OPI" in the oral fluid or urine of someone who has eaten lemon poppy seed loaf.

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Comments in the Gazette explaining the rationale behind these per se limits:

"For THC, the BDC offence levels contained in the Regulation are based, in part, on the advice of the Drugs and Driving Committee (DDC) of the Canadian Society of Forensic Science. The levels for LSD, magic mushrooms (e.g. psilocin/ psilocybin), phencyclidine (PCP), 6-monoacetylmorphone (6-MAM), and ketamine are set at “any detectable level.” These levels were recommended by the DDC as any presence of these drugs in the body is inconsistent with safe driving. The levels for GHB, cocaine, and methamphetamine are lower than those recommended by the DDC. This reflects the Government position that these are impairing illicit drugs and drivers should not have them at these levels in their body. The level for GHB reflects the fact that GHB can be produced naturally by the body. Therefore, “any detectable level” is not appropriate for this drug."

"Comments were varied and included concerns that the existing scientific evidence is insufficient to support a link between specific BDC offence levels and actual impairment. Others noted that different methods of consuming cannabis (i.e. smoking versus edibles) have different rates of absorption in the body. Some commented that the drug levels in the proposed Regulation are too high and would not capture all drug-impaired drivers, while others raised concerns that the drug level for THC is too low and may capture medical marijuana users who have a detectable level of THC in the body but are not impaired."