An official inquiry should be set up to look at effectively legalising cannabis and decriminalising the possession of all other drugs, a Liberal Democrat Party motion says.
The contentious idea will be debated at the Lib Dem Party conference in Birmingham next month.
However any official inquiry would need the backing of the Lib Dem’s coalition partners, the Conservatives.
The Home Office has previously rejected calls for a softening of drugs laws saying decriminalisation is not the answer.
Responding to the new call, Conservative MP Charles Walker said: “It is obvious that drugs do a great deal of harm.
“Drugs should be illegal because it sends the right message: that drugs are damaging.”
And David Raynes, of the National Drug Prevention Alliance, cautioned about the effect of cannabis, saying: “Our prisons are full of mentally ill people damaged by drugs, and cannabis is where they start.”
The controversial Lib Dem motion proposes that a panel should examine how to set up a regulated cannabis market.
It also proposes that an inquiry should look at whether possession of all drugs for personal use should not be a criminal offence.
Such an inquiry would also consider whether possession should still be prohibited, but police could only summon individuals to appear before panels tasked with determining education, health or social interventions.
Any motion passed by the Party at the conference would become official Lib Dem policy.
Nick Clegg is said to be “relaxed” about the plans. A source said: “He will watch the debate with interest,” and also commented: “It is perfectly sensible for a panel to look at these issues properly.”
In June a group of celebrities including Dame Judi Dench signed a letter urging David Cameron to decriminalise the possession of all drugs.
But a spokesman for the Home Office said: “We have no intention of liberalising our drugs laws.”
And highlighting the damage drugs cause, the spokesman added that, “giving people a green light to possess drugs through decriminalisation is clearly not the answer”.