Some countries have legalised cannabis, often with the hope of kick-starting a lucrative new source of tax revenue - but just how profitable has it been?
Aside from a few fact-finding trips, the prospect of legalising cannabis is not on the political agenda here in the UK - but could it be missing out?
Advocates say it's a bad call to let criminals continue to profit when legal businesses and the government could reap the financial rewards instead. Opponents counter that no amount of money is worth the associated public health risks.
But in the past decade countries including Canada, Malta, Uruguay and parts of the United States have decided to embrace the so-called green rush.
But how is it working out for them economically and what lessons could other places considering legalisation learn?
Reporter Datshiane Navanayagam talks to:
Christopher Snowden, Head of Lifestyle Economics at the Institute of Economic Affairs
Adam Spiker, executive director of a cannabis trade association in California
Amanda Chicago Lewis, a US based investigative reporter covering cannabis
Laura Schultz, executive director of research at Rockefeller Institute of Government in New York
Rishi Malkani, Cannabis Leader at Deloitte
Charlotte Bowyer, Head of Advisory at Hanway Associates
Producer: Ben Carter
Editor: Richard Fenton-Smith
Production co-ordinators: Helena Warwick-Cross and Maria Ogundele
Sound engineer: James Beard
