01/08/2015 04:16 BST | Updated 01/08/2016 06:59 BST

Yes, Psychoactive Substances Can Be Risky, But It Should Be for Individuals to Decide Whether or Not to Take the Risk

If the government proposed a law to ban horseriding on the basis that the activity carries a risk to human health, people would think it was bonkers.

Yet it has proposed prohibiting an even less risky activity: the inhalation of nitrous oxide.

The government's proposed Psychoactive Substances Bill would create the offences of "Supplying a psychoactive substance" and "Possession of a psychoactive substance with intent to supply". Only a few substances would be exempt: alcohol, nicotine and caffeine. Although the stated motivation for the bill is to reduce the use of novel psychoactive substances (NPS), legal highs used for decades such as nitrous oxide (laughing gas) and amyl nitrate (poppers) would be caught under the proposed legislation.

The risks of psychoactive substances vary considerably, but nitrous oxide has been described as "exceptionally safe" by David Nutt, professor of neuropsychopharmacology at Imperial College, London and former UK government drugs adviser. When inhaled via a balloon, the most common method of ingestion, serious health problems are vanishingly rare.

With this bill, the government has given up any pretence that it classifies drugs on the basis of harm. The reality is clear: this is a moral crusade. The government believes that altering your state of mind using psychoactive plants or chemicals is simply wrong. It doesn't care that the use of some drugs is much safer than the the use of others, or safer than other activities, like horseriding.

What of the exemptions for alcohol, nicotine and caffeine? When I wrote to the Home Office asking why they were excluding these substances, I got the following reply: "The means by which alcohol and tobacco are regulated is embedded in historical tradition and the tolerance of responsible consumption." Let's consider that. Drug policy is based on 'historical tradition' rather than, say, established science. And really the 'tolerance of responsible consumption' of alcohol simply highlights an irrational intolerance when it comes to other substances.

It's worth noting that the legislation is unlikely to even achieve its aim of reducing use of novel psychoactive substances. Since similar legislation was enacted in Ireland in 2010, NPS use has actually increased from 16% in 2011 to 22% in 2014, with use amongst young people the highest in the EU. It is true that a small number of people have developed health problems from the overuse of a few NPS that attempt to mimic established but currently prohibited drugs such as cannabis and MDMA. The best solution in this case is to make cannabis and MDMA available through legally regulated outlets, along with the provision of quality drug education on how to use these substances safely. There is, for example, no market for synthetic cannabis in the Netherlands where cannabis is sold from licensed premises.

The Psychedelic Society believes prohibition is an affront to the basic right of bodily autonomy: the right to do whatever we want with our own bodies. Yes, the use of psychoactive substances can be risky, but it should be for individuals to decide whether or not to take the risk. People should be able to buy, sell and use whatever substances they want, so long as there's no harm to others.

To show our support for the legal regulation of drugs as an alternative to prohibition, on Saturday, hundreds of people will gather outside Parliament for a mass inhalation of nitrous oxide. We'll charge our balloons, and as the clock strikes 3pm, we'll all inhale together in a sea of coloured rubber.

The fact is most people enjoy using drugs, whether nitrous oxide, coffee or alcohol, and that careful legal regulation is the fairest and safest solution. Rather than follow the failed path of prohibition, the government should be looking to the United States, where cannabis is now entirely legal in four states, with many more soon to follow.

The war on drugs is ending. Let's hope our government gets the memo.

Stephen Reid is the director of The Psychedelic Society