The news of Donald Trump’s election to the US presidency was a bitter pill for liberals across the world.

But look closely, and there was the thinnest of silver linings: Americans were quietly voting down the war on drugs in a series of popular ballot initiatives.

The number of states providing legal cannabis to medical patients rose to 28 plus Washington DC. And in California, Nevada, Massachusetts, and Maine, voters approved the idea that cannabis should be available to adults for recreational use. Incredibly, the country that invented and propagated the war on drugs has now legalised the sale of cannabis in eight of its states.

It’s a world away from the UK. Last week saw the publication of a report from VolteFace and the Adam Smith Institute calling for the sale of cannabis to be regulated and taxed. This provoked the usual knee-jerk reaction from the government, that “cannabis is illegal because it is harmful”.

I never cease to be amazed by people’s instinctive reflex that unpleasant things can simply be removed from this world by “banning” them. The idea that cannabis can be eradicated from our society through the action of the criminal law flies in the face of 50 years of evidence of the failure of prohibition. No country has even got close. As we saw with alcohol in 1920s America, banning something that people enjoy doing doesn’t stop them from wanting to do it: it simply creates a criminal market to service that demand.

In the case of cannabis, the UK’s most popular drug, it’s a thriving multi-billion pound criminal industry. The winners are some of the most unpleasant characters in the country; the losers are millions of otherwise law-abiding people who face debilitating criminal records, arbitrary stop and search, and (for the unlucky few) a spell in prison.

The Home Office and other inadvertent cheerleaders for organised crime like to employ the argument that reformers think of cannabis as “harmless”. On the contrary, we know there are risks both to physical and mental health. A small proportion (9%) of those who use cannabis go on to become dependent — much less than for alcohol (15%) or tobacco (32%), but significant nonetheless. Many of the health problems stem from the market dominance of “skunk”, which is high in THC (the intoxicating part) and low in CBD (a naturally-occurring anti-psychotic). Skunk itself is a product of prohibition, which drives producers towards high potency, low volume products just as prohibition-era bootleggers trafficked hard liquor rather than beer.

The question is, how best to deal with these harms?

The alternative to criminal profiteering is legal regulation. The prohibitionists want you to believe that regulation means less control. If that was true, then we would be merrily deregulating pubs, casinos, building sites, airline safety, you name it, in the mistaken belief that less regulation equals more safety.

We don’t regulate harmlessness; we regulate harms. Cannabis, like all drugs, can be harmful, which is precisely why it should be regulated. At the moment, give or take the occasional seizure, raid or arrest, the government has no policy levers whatsoever over the cannabis trade.

What kind of levers could we have? Well, let’s start with the product. We don’t have to legalise skunk in its current form. We could, if parliament wanted to, impose an upper limit on potency, and a minimum limit on the anti-psychotic CBD which seems to ameliorate most of the negative effects. In other words, we could use the tools of the regulator to regulate “skunk” out of existence, and usher in a range of alternative products, including milder strains.

Next, if we wanted to, we could use legal regulation to push people away from smoking cannabis and towards healthier forms of consumption, from vaping to edibles. In Colorado, where cannabis has been legal since 2012, the market has evolved rapidly. More than half of the product sold there is now in the form of concentrates and other non-smokeable forms of cannabis.

Lastly, regulation could do a better job of keeping cannabis out of the hands of children. We know that heavy cannabis use in teenage years is particularly problematic. Dealers don’t ask for ID, but licensed premises do. Regulators would conduct spot checks and remove people’s licenses if they were found selling cannabis to under-18s.

It won’t all be plain sailing. While aggregate harms could be brought under control by making the product safer, commercial interests will try to exert influence over the drafting of the regulations, as they have done for alcohol and tobacco, and will seek to encourage higher levels of use. But the painstaking business of reconciling profits with public health is exactly what government does in so many other areas of life, and it’s a whole lot better than the alternative of leaving it to organised crime.

The United States is showing Europe the way on this issue, if on little else at the moment. California, the sixth-largest economy in the world, has turned the page on regulation. Canada is set to legalise next year. It is only a matter of time before the UK follows suit. In the meantime, let’s have a serious debate about regulation.