On October 17, Canada became the first large economy to legalise recreational weed. (Uruguay blazed the trail in 2013.) From November 1, doctors can prescribe medical pot on Britain’s National Health Service. Thirty US states have already legalised medical cannabis, while nine allow recreational use and Donald Trump has signalled that he supports decriminalisation at a federal level. Cannabis could soon become a normal part of daily life across the anglophone world, just like alcohol or coffee, displacing cigarettes, which are becoming socially unacceptable. Judging by nearly 50 years of Dutch decriminalisation, is this a good thing? And can pot treat our pain and ailments?