The British government has announced that poppers – a recreational drug – will be exempt from the coming clampdown on “legal highs”, to be introduced next month.

Poppers are popular for use during sex, and are especially widely used by gay men. In a recent debate on the bans, gay Tory MP Crispin Blunt outed himself as a poppers user. The government reversal comes following an intervention by the Advisory Council on the Misuse of Drugs (ACMD), which advised that poppers may not be a drug under the definition used in the new law.

It is to be celebrated that at least one drug will be spared the ban, but the exception only serves to highlight the ludicrous nature of the law. At a stroke, thousands of diverse substances will be made illegal to supply. The law is not drafted to deal with harmful substances, but all psychoactive substances, regardless of whether they are harmful or not – this makes a mockery of government claims that the bans are an attempt at harm reduction.

In fact, such bans tend to increase, rather than reduce drug harm, by criminalising the supply chain and reducing government ability to regulate drugs. Users often substitute one drug for another – so for example, cocaine usage fell when mephedrone was legally available. This fact didn’t stop the then Labour government from banning mephedrone (against the advice of the ACMD), no doubt to the relief of the cocaine trade.

British governments have a long history of pointless – and often dangerous – drug bans. Questionable decisions in recent years include the bans on magic mushrooms and khat – neither considered to be dangerous. But they have never, until now, tried to ban so many substances at a stroke. The repercussions are impossible to predict; but one can guess that again, the cocaine trade will benefit.

We can be relieved that some common sense was seen in the poppers exemption. But common sense and government drug policy are rarely found in each other’s company. At a time when cannabis is being legalised in a number of countries, Britain feels increasingly backward.