WHAT should we do to minimise the harm cannabis can cause to the health and welfare of users and to society at large? One answer, according to a report by a group of prominent academics and government advisers, is to change the law to allow the state to prepare and distribute the drug for recreational use.

This proposal is the most controversial of several recommendations from a commission assembled by the Beckley Foundation, a British charity dedicated to exploring the science of psychoactive substances. “The damage done by prohibition is worse than from the substance itself,” says Amanda Feilding, …