CANNABIS should be legalised in the UK. Even if you don’t agree with me, I hope you at least think this country deserves to have an intelligent conversation about cannabis and the law.

We’re now at the moment when this conversation can take place. In two weeks, doctors in Scotland, Wales and England will be able to prescribe medicinal cannabis. The rule change – at UK level, as drug laws are reserved to Westminster – comes in the wake of a number of high-profile cases of epilepsy sufferers who were found to be helped by medicinal cannabis. Dozens of other nations, as well as 30 US states, also allow medicinal use.

There are many reasons why legislation needs changed over the recreational use of cannabis as well. Let’s start with law enforcement. If cannabis were legalised a hole would be blown in organised crime. Today, anyone who consumes cannabis is financially propping up organised crime. The gangland shootings you read about – those involved will be key players in the UK cannabis trade.

Internationally, the cannabis trade is blood-soaked. Moving hashish into Europe, and across the continent, is a murderer’s racket. Every tonne of hashish has a cost in human suffering.

Legalisation of cannabis could work like a reverse of prohibition in America. Prohibition spawned racketeers, legalisation of cannabis could curb gangsterism.

Keeping cannabis illegal forces consumers to interact directly with organised crime. I’ve reported on crime for many years, and it is a sad matter of economics that middle-class users tend to buy from “nice dealers” – the friendly, laid-back hippie in the student quarter – but low-income users will be forced to buy from the thuggish dealer in the block of flats across the road. The poorest in society, if they choose to use cannabis, are not only rubbing up against a world of violence, but more likely also a dealer selling much harder drugs.

It should also be noted that the nice hippie drug dealer has to get their cannabis from somewhere too – namely, a higher up dealer involved in organised crime. Creating a black market sullies everyone. Legalise the product and keep those who wish to use cannabis away from predatory criminals. Keeping the average consumer away from the criminal underworld will prevent potential personal escalation of drug use. If cannabis were legal someone who wants to smoke a joint wouldn’t have to risk buying from a dealer who also sells heroin.

It is the organised crime dealer who is the gateway to harder drugs, not cannabis. Cannabis is no more a gateway to heroin than alcohol or tobacco.

Now, let’s look at the ubiquity of cannabis. If we’re honest we know that the drug is everywhere in society. You may never have used cannabis, but you’ve certainly smelt it walking through city streets. People from every walk of life have used or do use cannabis – politicians, police officers, taxi drivers, chefs, writers, actors, teachers, accountants, lawyers, medics, bar staff, charity workers, shelf-stackers, academics, carers, call centre workers, civil servants.

The UK behaves like a prissy parent who knows something unseemly is going on in their kid’s bedroom but is too scared to talk about it – so the kid continues to experiment, and mum and dad turn a blind eye. So let’s talk about it, and here’s what we need to say: people are using cannabis the length and breadth of the country – why are we making them criminals?

Then there’s the issue of economics. Britain’s cannabis black market runs to £2.6 billion a year. If we legalised it, that would be £2.6 bn taken away from gangsters, murderers, people traffickers, arms dealers, pimps, and racketeers – £2.6bn that could be taxed, and taxed heavily. All those nice hippie dealers? They could work in a new, highly-controlled, government-supervised industry which creates jobs, makes sure consumption of the product is safe, and pours buckets of cash into the Treasury.

The economic argument is the least important though – it simply provides a financial incentive. The main reason for legalisation is safety. The hashish imported into the UK is sodden with impurities – oil, saw dust, soil, God knows what. Hydroponic skunk – plants grown in indoor “cannabis farms” – contain much higher levels of THC (the psychoactive ingredient) than the marijuana of old. If cannabis were legalised these safety issues could be dealt with – think of the difference in product between moonshine liquor made illegally, and a shop-bought bottle of vodka.

In terms of health and social consequences, studies have shown that alcohol causes greater damage to the body than cannabis. It is also rare to hear of someone smoking a joint and then beating their spouse, unlike alcohol.

However, none of this is a “cannabis is good for you” argument. Quite the reverse. Cannabis isn’t good for you – it’s bad for you like alcohol, tobacco, and sugar. But people are attracted to bad things, that’s human nature – only in this case we’ve thrown cannabis outside the law, and therefore away from the realm of control, regulation, education and consumer protection.

Legalisation would also remove the dark glamour of cannabis – it would no longer be taboo, and would become no more exotic than a glass of wine or cigarette. Young people under 24 are shunning alcohol in ever greater numbers. It would follow that those reluctant to get drunk are unlikely to rush to use cannabis if it were legalised.

However, it’s important that people like me who advocate legalisation need to be aware that such a change will create its own problems. Legalisation is not a panacea. In a legal landscape, there will inevitably be adults who go into a “cannabis store” to illegally buy marijuana for the underage, just as happens now with alcohol; those who might never have tried cannabis may experiment; some will use it too much. Are those problems worse than the current state of affairs – where criminal enterprises create greater and more dangerous problems? I would answer no, which is why I think a national debate on the legalisation of cannabis needs to start now.

Cannabis is already legal or decriminalised in Canada, Uruguay, Spain, Portugal, the Netherlands, Switzerland, and Norway. Eight US states also allow cannabis use recreationally. The march of history points one direction – and that is to legalisation.