Medical marijuana is nothing new in America: last month, TV networks even aired the first ad to promote a medical marijuana website. Now, a pro-legalisation ad campaign has hit the streets of London, complete with advertising vans calling for cannabis to be legalised, regulated and taxed.

The vans will be cruising around Central London for three days (we saw them just this morning at Old Street roundabout), and is funded by Cannabis Law Reform (Clear), a group that is calling for the government to rethink their stance on cannabis. They've even got a YouTube commercial, which you can watch below: 

Clear's message is pretty clear: the black market for marijuana is worth £6 billion – so why not subject it to tax and regulation, make it available for medical use, and keep dealers off the streets in the process? 

"This is a campaign aimed at politicians and the media, or people who don't understand cannabis," says Peter Reynolds, the chairman of the pressure group. "The prohibition of cannabis causes far more harm than it prevents. Ultimately, the illegality of cannabis is making people with guns rich. We need to get the dealers off the streets and take the market out of the hands of the criminals – cannabis needs to be properly controlled, labelled and accurately weighed."

Some advocates for drug legalisation often argue that all drugs should be made legal to reduce crime rates and prevent the consumption of impure drugs cut with dangerous substances like rat poison, bleach or even levamisole, a drug used to deworm cattle. "Although my concern is cannabis, I'd agree with legalising all drugs," says Reynolds. "In fact, the more dangerous and harmful a drug is, the important it is that it's legalised and regulated. Thousands of people would benefit from the medicinal qualities of the drug."

What do you think? Should we legalise cannabis?