Ontario judge rules legal limit for THC impairment is constitutional

Earlier in April, a Brampton judge overseeing the trial of a driver who struck and killed a woman and her three young daughters in a 2020 crash has rejected his challenge of the law on cannabis-impaired driving.

Last year, Brady Robertson had pleaded guilty to four counts of dangerous driving causing death in connection with the June 18, 2020 collision resulting in the death of Karolina Ciasullo and her three daughters. However, he had pleaded not guilty to four counts of operation while impaired by drugs causing death, and his lawyers filed a constitutional challenge of Canada’s law setting out a legal limit for THC blood concentration when driving. Specifically, Robertson’s lawyers argued that the legal limit of five nanograms of THC per millilitre of blood is arbitrary, overboard, and does not correspond to impairment.

In addition, Robertson’s defence lawyer Mayleah Quenneville argued that limit runs the risk of not only catching people engaging in risky behaviour but also those “morally innocent” people who use cannabis for medical reasons, and who use responsibly but still have residual THC in their blood. Moreover, his defence lawyers also noted the possibility that frequent cannabis users could have residual THC levels beyond the legal limit, despite not being impaired when tested.

Ontario court Judge Sandra Caponecchia had provisionally convicted Robertson on four counts of impaired driving causing death, after it was determined that Robertson had a blood THC concentration of 405 ng/ml about 45 minutes after the crash, but noted that the verdicts were “subject to the outcome of the constitutional challenge.”

In a subsequent ruling in April, Judge Caponecchia rejected that challenge after determining that the legal limit complies with Robertson’s charter rights.

Furthermore, she noted the challenge raises “complicated policy considerations,” concluding that although the legal limit may affect some frequent and chronic users of cannabis, “it does so in a way that does not violate the principles of fundamental justice because on balance, the impact is neither arbitrary, nor overboard.”

“The impact is consistent with Parliament’s stated intention when the possession of cannabis was legalized: to strengthen the laws with a view to not only detecting impaired drivers but also deterring individuals who consume cannabis from getting behind the wheel of a car when they represent a risk to the public,” states the ruling.

In her ruling, the judge also said it cannot be assumed that a THC reading of 5ng/ml reflects a “harmless amount of residual THC level,” in contrast to the evidence of recent consumption, in every frequent cannabis use. “Blood can only be seized when there are reasonable grounds to believe an offence has been committed,” the judge concluded.

2 responses to “Ontario judge rules legal limit for THC impairment is constitutional

  1. 405 ng/mL in blood 45 minutes after the accident using normal THC metablic rate would suggest the guy had just smoked or was beyond stoned when he hit her. His blood concentration at impact would have probably been 1000 ng/mL plus for it to be at 405 ng/mL 45 minutes later

  2. Medical Cannabis users can run at blood levels of 10 to 50 ng/ml of THC and even higher in some cases.
    Assumption of impairment also ignores levels of CBD which have a major mitigating factor in the psychoactive effects of THC.

    Many aspects of the new Canadian Cannabis Act impairment laws are brutally unconstitutional and will continue to be challenged in court due to the vast range of human tolerance to THC and the inconsistency of it’s impact on various individual human physiology.
    In the vast majority of medicinal applications, the daily use of Cannabis medicine results in a n almost complete and total tolerance to the psychoactive effects of Delta 9 THC due to the receding of CB1 receptors in the central nervous system, specifically in the brain, resulting in no impairment in the ability to operate a motor vehicle while using Cannabis medicine properly.

    As an abstainer from alcohol I find it VERY disturbing that current legislation dictates brutal, unjust, and immoral punishment of drivers for THC blood levels of 2ngs or higher because they seem to be under a brutally FALSE ASSUMPTION that blood level of THC is directly related to level of personal impairment; AND that Cannabis impairment is somehow similar to alcohol impairment! This kind of mentality is patently absurd from the perspective of one who has used cannabinoid therapy daily to function normally for well over a decade and has given up the use of alcohol in the process.

    I in no way endorse the carte blanche use of Cannabis while driving; BUT I do know from personal experience related to the medicinal use of cannabis, that to compare the impairment level, and universality, to that of alcohol is not only absurd, it is a violation of EVERY individual’s human rights, especially that of medical cannabis patients!

    This will continue to increase the multitude of court cases due to the erroneous assumption that Delta-9 THC causes universal impairment in humans.

    Cannabis impairment is so vastly different, (and non-consistent) from virtually every other type of drug impairment, including alcohol, that to compare them is actually kind of ridiculous.
    The range of impairment goes from Zero to totally impaired. One individual can have 50ng/ml and be perfectly coherent and functional and another can have 5ng/ml and be completely impaired.
    The identification and removal from the road, of drivers that are actually impaired by Cannabis use will not be easy but arbitrarily locking up cannabis patients is just going to punish innocent people even more and cost everyone a great deal in court challenges.

    I suspect there will also be court challenges on recreational use alone that will not go well for the government simply because the currently proposed laws on cannabis impairment are based on false science and false assumptions.

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