Some cannabis users continue to buy the drug from illegal sources for years after it is possible to purchase it from regulated, legal shops, because the illegal sources can be cheaper or easier to access, a survey in Canada and the US has found.

The findings suggest that policy-makers who want to wipe out the cannabis black market need to make sure that new legal sources are competitively priced and widely available.

Cannabis has recently become legal for recreational use in several countries including Canada, Mexico and South Africa as well as in 18 US states. Advocates of legalisation say it is less risky for users to buy cannabis from regulated shops because their cannabis products are safer than those from illegal dealers, with better dose labelling and quality-control measures, and the shops are less likely to sell to minors.

But not all users choose to buy from the regulated shops. Canada, for instance, legalised cannabis in 2018, but by 2020, about half of all cannabis used in the country was still being obtained illegally.

The new survey, of nearly 12,000 cannabis users in Canada and the US, found that price was the most common reason for buying illegal weed, cited by about 35 per cent of users in Canada and 27 per cent in the US. Convenience was the second commonest factor, cited by 17 to 20 per cent of respondents across both countries. [Read more at NewScientist]