Nick Clegg has said he wants to effectively decriminalise the possession of almost all drugs, and a senior Liberal Democrat aide told BuzzFeed News that Conservative drugs policy is "based on the Daily Mail rather than the evidence".
The deputy prime minister appeared alongside pro-legalisation businessman Sir Richard Branson at an event in London on Wednesday and announced that the Lib Dems would turn drugs policy into a health, rather than a criminal, matter.
Clegg said the Lib Dems would "end the use of imprisonment for possession of drugs for personal use" and shift responsibility for drugs policy from the Home Office to the Department of Health.
The Lib Dems would also make the Advisory Council on the Misuse of Drugs – the group of experts who offer guidance on what drugs should be illegal – independent of government, to stop ministers from meddling with its findings.
"The UK and its partners must acknowledge that the 'war on drugs' hasn't worked," Clegg told an audience at Chatham House. "Despite the decades of tough talking and billions of dollars spent in waging this war, the global drug problem and the criminal markets that underpin it remain all but untouched by our enforcement efforts."
But the party's ability to actually enforce the new policy, which is expected to be in its manifesto, will depend on the Lib Dems' role in any future coalition government, and one senior Lib Dem aide told BuzzFeed News that the party has been repeatedly blocked from liberalising drugs law by the Conservatives.
"We pushed the issue massively in this coalition but we've been thwarted even at the smallest end of the scale by the Conservatives," they said. "[Home secretary] Theresa May is very staunchly in that camp but there are very few allies. They have no interest in grappling with this difficult and controversial issue because their policy is based on the Daily Mail rather than the evidence."
But in a sign that it's still hard to sell a liberal drugs policy in the media, the Lib Dems are keen to avoid their policy announcement being seen as decriminalisation. Instead, aides emphasise that they would continue to prosecute drug dealers.
Under the plan, drug offences would be treated as a civil offence and a health issue in all but the most severe of cases. People caught in possession of drugs would be ordered to undertake health treatment, be educated about the dangerous of drug use, or pay a fine.
Clegg's spokesperson declined to comment when asked whether the deputy prime minister had himself taken drugs, and said everyone has a right to a private life before politics.
This is the Lib Dems' new policy towards drugs:
Adopt the approach used in Portugal, where those arrested for possession of drugs for personal use are diverted into treatment, education or civil penalties that do not attract a criminal record.
Legislate to end the use of imprisonment for possession of drugs for personal use, diverting resources towards tackling organised drug crime instead, as a first step towards reforming the system.
Continue to apply severe penalties to those who manufacture, import or deal in illegal drugs, and clamp down on those who produce and sell unregulated chemical highs.
Establish a review to assess the effectiveness of the cannabis legalisation experiments in the United States and Uruguay, in relation to public health and criminal activity.
Legislate to make the Advisory Council on the Misuse of Drugs independent in setting the classification of drugs, while remaining accountable to Parliament and the wider public.
Enable doctors to prescribe cannabis for medicinal use.
Put the Department of Health rather than the Home Office in charge of drug policy.