With legalization of cannabis in Canada due to take effect in July 2018, the police are concerned that they do not yet have the means to test reliably whether drivers are impaired by the drug beyond a safety limit.
In fact, the RCMP has asked for an extension of the legalization date on those grounds.
However, the police may be operating under a false premise, that legalization will increase marijuana use creating a greater level of driver impairment. Legalization certainly means greater availability, but there is no evidence to connect availability and increased use.
Also, marijuana is easily available already through dispensaries and on the black market. That there are an estimated 2.3 million marijuana users in Canada attests to its current availability.
Still, the police are concerned that they will be unable to verify whether a driver is unsafe to operate a vehicle because of marijuana use by the time it is legalized. The RCMP admits that “the mere presence of a drug in the sample does not constitute sufficient evidence to charge a person with being impaired by a drug.”
Just as there is a legal safety limit to how much alcohol a driver can have, surely there should be a similar limit for marijuana use. But how will this limit be determined?
According to an article in Scientific American, “the issue of stoned driving remains enormously complex, with experts still highly uncertain about marijuana’s precise effects on cognition and competence.”
There are marijuana detection devices in the making. For example, a California company called Hound Labs has developed a portable device to register cannabis use from breath samples.
Other devices being tested will use saliva samples.
There will need to be a device that can determine a safety limit for the drug, but this might not be forthcoming yet because of the medical and legal issues involved.
John Rowell
Nelson