In Swindon a young man lies in hospital critically ill after taking a green pill stamped with a dollar sign [see footnote]. Last weekend a 15-year-old girl in Oxford died after taking a drug she thought was ecstasy. Just days earlier there was the inquest into a teenage gym instructor so badly injured after suffering spasms during an overdose, police initially thought he had been murdered.

Already this year about 20 people have been killed after taking what they thought was ecstasy, with seven deaths in Scotland over the past two months alone. These fatalities exceed recent annual tallies of ecstasy-related deaths – for all the scaremongering, ecstasy is a comparatively harmless drug, less dangerous than alcohol or tobacco. Sadly, in many cases the pill popped turns out to be the far stronger PMA, which takes longer to kick in, so users may take another, with catastrophic results.

These unfortunate youngsters seeking the thrill of intoxication are victims of prohibition. They are dead because our nation continues to wage a war on drugs launched four decades ago by a crooked US president; a war that drives users underground and prevents regulation of products ingested by millions each weekend. If it was contaminated olive oil killing the nation's kids, there would be an outcry; instead, those victims are "druggies", blamed for their own deaths.

Yet our society encourages an illegal market to boom, as shown by the cost of ecstasy halving in a decade, while the world's most brutal gangsters cream off huge profits and reduce the purity of their products. Politicians shun the evidence of scientists and ignore the devastating impact of their stupidity: only this month the coalition made the myopic decision to ban qat, a mild stimulant, though experts said there was no need, and east African farmers warned this will drive them towards destitution.

So we would do well not to get over-excited by the welcome news that drug use is falling, with younger generations clearly more censorious than their elders. Britain still has among the highest rates of use in Europe, with one in 12 adults and one in six older teenagers admitting to taking an illegal drug last year. This means each weekend huge numbers of people put their lives in the hands of people who use murder and mayhem to promote their business

Despite the recent spate of deaths, this country escapes the worst consequences. On Sunday there are elections in Mali, the first step in rebuilding a democratic nation that collapsed into coup and chaos last year after South American drug barons began using it as a path for their trade into Europe. Slowly but surely corruption corroded the country's institutions. The mercifully brief legacy of this was the world's first al-Qaida-controlled state.

Next time you hear politicians talking about the war on terror, remember how their war on drugs backfired in such lethal style. Mali is not alone: Guinea-Bissau is a fully fledged narco state; while organised crime, maritime piracy and militant Islamism grows across the region. Meanwhile, central America – the transit route for cocaine to all those wealthy drug users in the north – has degenerated into the world's most violent region, its cities like war zones. Honduras, with fewer than 8 million inhabitants, has more homicides than the entire EU, home to almost 500 million people.

Such facts are met with silence by the aid lobby, so fearful of upsetting their political paymasters despite the damage prohibition causes across the developing world. They are also brushed aside by Britain's leaders with meaningless messages of abstinence – until they leave office, when some have sudden conversions and express surprise to find the public mood so much maturer than the one at Westminster. If there was any justice, our political masters would be prosecuted for wasting police time on a war that can never be won.

Increasing numbers of police officers acknowledge that archaic drug laws make their job tougher by boosting the profits of gangsters, criminalising millions of otherwise law-abiding people and inflaming racial tensions. The one thing they fail to do is stop people from taking drugs: just look at Scandinavia, with similar addiction rates in Sweden and Norway despite wildly differing approaches. They are even more pointless in a digital and global economy, when users can order newly created narcotics online from vendors based abroad. Yet still the delusion exists that the supposed scourge of drugs can be defeated.

One day people will look back on this era with bemusement, just as we do at those days when alcohol was banned in the US. Already drug possession has been decriminalised in Portugal and the Czech Republic, while even the US has begun experimenting with more sensible drug laws. In May the Organisation of American States issued a landmark report exploring the path from prohibition, reflecting concerns of leaders fed up with chaos and carnage in their countries. As the pope tours his native region and warns against lifting controls, Uruguay prepares to vote next week on becoming the first country to fully legalise cannabis, with state-controlled outlets and regulation of users.

Perhaps we are finally on the brink of allowing reality to break through the fear-filled propaganda that has shrouded the debate on drugs, spreading death, decay and devastation around the globe. But what a long, strange trip it has been.

• This footnote was appended on 29 July 2013. At the time of writing this article, the young man in Swindon referred to in the first sentence was still critically ill in hospital. Tragically, he died shortly afterwards.