Canada Marijuana Legalization Plan Sets THC Driving Limit at 5 ng/ml

The Canadian government has released their plan to legalize marijuana, and it’s mostly good… mostly.

The plan includes legalizing the possession, personal cultivation and licensed distribution of cannabis for those 18 and older. However, an unfortunate part of the proposal – which is expected to take effect July of next year – is that it would set a specific driving limit for tetrahydrocannabinol (THC), one of the main compounds found in cannabis. This is an unscientific approach, given that studies show no clear correlation between THC in the blood and impairment like we see with alcohol.

The 5 ng/ml limit for THC is identical to that set in Washington when the state legalized in 2012; at the time the limit was strongly opposed by many marijuana advocates. None of the other seven states that have legalized cannabis after Washington have set the same limit. The limit means that if someone has at least 5 nanograms of THC per milliliter of blood – a small amount – they are guilty of driving under the influence, regardless of whether or not they are actually “high” or impaired. The ideal method of determining if someone deserves a DUI is to make law enforcement prove impairment, which is the case in most places.

Marijuana legalization advocates in Canada who oppose an arbitrary driving limit for THC should be in contact with lawmakers and Prime Minister Trudeau to ask them to avoid setting a specific limit for THC as their proposal would do. Luckily the THC limit is introduced in a measure separate from the legalization bill, meaning lawmakers could technically approve of legalizing marijuana without accepting the limit.

1 comment

    • Michael Francesco on April 14, 2017 at 11:12 am
    • Reply

    Absolutely! I read an excellent article the other day about this called “why a 5 ng/ml limit is bad public policy”. Everyone processes pot differently, and it is completely unscientific (see the recent AAA study). It will nail innocent people, including medicinal patients who are truly sober as a gopher, and will allow some people to get away with driving higher than a rollercoaster.

    A good approach would be to determine impairment with a standardized field test (walk the line, say the alphabet, stand on one leg, count 30 seconds et.c.) followed by a test to determine the PRESENCE of any drug IF the driver fails the sobriety test. This “tandem per -se approach” would ensure that nobody can evade DUI charges even though they were clearly unfit to drive, as well as protect those who use marijuana responsibly, including medicinal patients who may under the proposed approach face criminal charges. How is someone who smokes pot medicinally supposed to know if they are over some arbitrary limit? The only safe option for medicinal marijuana patients would be to never drive regardless of how sober you are, and that is unacceptable.

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