The all-party parliamentary group on drug policy reform undertook an inquiry into the implications of the arrival of "legal highs" – a new substance appeared on the UK market every week in 2012. The prime minister says the current policy is working. I wish it were. But as the use of cannabis has declined by a few percentage points over the past few years, the use of "legal highs" has soared. The position for drugs users is therefore more dangerous than it was a few years ago.