The Liberal Democrats have set up an independent panel of experts to look into how a legalised market for cannabis could be beneficial for the UK. The party's health spokesperson Norman Lamb, founder of DrugScience, Professor David Nutt, and former deputy assistant commissioner of the Metropolitan police, Brian Paddick, are among those who will be looking into how to develop a workable model for the sale and taxation of cannabis.

The panel, chaired by Steve Rolles, senior policy analyst of Transform Drug Policy, will also approach international experts to discuss how they have implemented models in areas such as Washington and Colorado in the US and Uruguay. The announcement arrives as MPs are set to debate the possibility of legalising the production, sale and use of cannabis after a parliamentary e-petition attracted more than 220,00 signatures.

Lamb said that to make the case for the UK implementing a free cannabis market, the evidence must include successful examples from other countries and plans on how to minimise the harm that cannabis can cause to health. He said: "I share people's concerns about the health impacts of any drug – legal or illegal. But we can better manage that harm by taking the money that's currently spent on policing the illegal cannabis market and spending it on public health education and restrictions at the point of sale. That's the approach we've taken with cigarettes and it's led to dramatic reductions in smoking in recent years.

"With successful legal cannabis markets emerging in different parts of the world, the onus is now on the supporters of prohibition to explain why we shouldn't do the same things here in the UK. We must end the hypocrisy of senior politicians admitting to using cannabis in younger years – and describing it as 'youthful indiscretions' – whilst condemning tens of thousands of their less fortunate fellow countrymen and women to criminal records for precisely the same thing, blighting their careers."

It is highly unlikely the Tory government will declassify the Class B drug. Responding to the petition, it said "substantial scientific evidence shows cannabis is a harmful drug that can damage human health". The party has also imposed stricter drug laws since it came into power following the May general election, with a crackdown on so-called 'legal highs' becoming one of the first policies introduced – a move Lamb previously described to the IB Times UK as "ridiculous".

He added: "I totally oppose the Tories' plan to, in effect, introduce a prohibition on legal highs. That's going to create more problems and create another new criminal class."

Stuart Harper, political liaison officer for cannabis reform campaign group NormlUK said: "The regulation of cannabis in the UK is long overdue. For access to such a safe therapeutic substance to have been restricted for so long is a travesty. Providing relief and relaxation to millions, cannabis is the second most popular recreational substance after alcohol. To assume that this kind of market is safer or more restrictive when conducted in the illegal shadows, when compared to the legal and age-regulated markets in countries and states from the EU to the US, is sheer folly."