In the US presidential debate of the excluded three years ago, the Green Party, Justice Party, Libertarian Party and Conservative Party, four entities from right across the political spectrum, were united in denouncing the lunacy of the War on Drugs. Meanwhile Barack Obama and Mitt Romney, divided by far less ideologically, remained wedded to the status quo. It encapsulated a depressing truth about drugs policy in the western world. Advocating reform is a favourite of fringe and retired politicians and police officers. Those in power are lamentably reticent.

So it is in the UK. Last year promised to bring a sea change in the UK's self-destructive approach to the War on Drugs. A non-binding vote in the House of Commons advocated rethinking drug laws and - against Theresa May's wishes - the Home Office produced a report on what works in drug policy. It confirmed what we already knew: harsh sentencing does not lead to reduced use of drugs and, by stigmatising drug users, is actually counter-productive.

But it is a lesson that the main parties appear not to want to learn. While the Lib Dems and Greens advocate fundamental change in the UK's approach to drug policy - both parties want to transfer drug policy from the Department of Health to the Home Office, and the Lib Dems want to borrow from the successful Portuguese model, and decriminalise possession of all drugs for personal use - the bad news is that the Conservatives and Labour seem to remain wedded to the failed status quo on drugs.

Blind to the findings of the Home Office's report, David Cameron claimed that existing drug policy is "working". The fact that someone is 20 times more likely to die from drugs in the UK as in Portugal, where drug possession was decriminalised in 2001, tells a very different story. But the Conservative manifesto ignores all these lessons, advocating doubling down on failed drug policies that treat personal drug users as criminals rather than addicts. Abstinence would be kept as the goal of drug treatment, and substitute drugs to wean addicts off the most dangerous ones would not be countenanced.

Ostensibly Labour's approach seems less cackhanded. The manifesto advocates a greater emphasis on drug treatment and less on punishing users. "We will ensure drug treatment services focus on the root causes of addiction, with proper integration between health, police and local authorities in the commissioning of treatment," it reads. But of course very few people read manifestos. So what matters is the message that Labour is sending out - and campaign posters attacking the Lib Dems as "soft" on drugs shows that the party has opportunistically spied a dividing line with Clegg's party by hammering its desire to reform drugs policy. “Accusing the Lib Dems of being ‘soft on drugs and thugs’ is a cheap populist slogan that tries to hide the Labour Party's own co-responsibility for destroying the future of thousands of people by giving them a criminal record for no good reason at all," Martin Jelsma, Director of the drugs policy programme of the Transnational Institute, recently told me.

The alternative is hardly earth-shattering: following the evidence of what actually works in drug policy, rather than mindless tub-thumping. But political expediency dictates that the Conservatives and Labour do not speak out against the disastrous status quo. While that remains the case, 3,000 people will die every year from drug use in the UK.