MPs will admit to the failure of the war on drugs tomorrow, in one of the most important developments in the debate for a decade.
Leaked accounts of the home affairs committee report into drug use suggest the influential group of MPs will call for David Cameron to set up a royal commission to draw up changes to the law.
"The general view [of the committee] was that the drug laws in Britain are all a bit outdated. We have a Drugs Act that's really outlived its usefulness and that really belongs in the 1960s and 1970s," a source told the Daily Mail.
"It seems to deal with the drugs world as a fairly simple market with a relatively small number of controlled substances out there. But that's not the case."
Britain was "fighting a losing battle over drugs policy", the MP added.
The report comes ten years after the committee's previous examination into drugs laws called for ecstasy to be legally downgraded. The proposal was flatly rejected by then-home secretary David Blunkett.
This report is fortunate enough to fall on what should be more sympathetic ears. David Cameron called for drug liberalisation when he first became an MP and Nick Clegg is thought to be privately sympathetic.
But with the Tories currently being split in two by MPs' views on gay marriage, the prime minister will be loathed to put his reputation on the line campaigning for another controversial liberal measure.
The option of a royal commission would make gradual reform of the current laws as palatable as possible. The commission would not report until just before the next election in 2015. Its recommendations would not have to be adopted, but its clout means it would be difficult to ignore.
The home affairs committee report comes amid sea-changes in the international outlook for drug liberalisation. Guatemalan president Otto Perez Molina became the first acting world leader to call for deregulation recently, followed quickly by support from Mexico and Colombia.
The three countries are particularly important as their territories have become acutely unstable due to the drug routes winding their way through South and Central America into the US.
Washington and Colorado recently decriminalised cannabis, in a move which observers expect to see repeated in other states.
Portugal's experiment in turning drug laws into 'administrative offenses' also saw impressive results, with falls in non-related criminal offences, general drug usage and HIV transmission through dirty needles.