Recently re-elected Vancouver Mayor Gregor Robertson has joined four of his predecessors who recently came forward with a call to revise Canada's marijuana laws.

The mayors – Mike Harcourt, Philip Owen, Larry Campbell and Sam Sullivan – signed an open letter this week asking "all elected leaders in British Columbia to speak out about the ineffectiveness and harms of cannabis prohibition."

On Thursday night, less than a week after Robertson's sweeping civic election victory that saw every candidate on his Vision Vancouver slate elected, the current mayor sent a Tweet supporting the bold move.

"Good to see 4 Vancouver ex-mayors calling for end of cannabis prohibition. I agree, we need to be smart and tax/regulate," he wrote.

The letter blames Canadian laws for driving a massive criminal market, citing a Fraser Institute study that estimates the annual value of B.C.'s marijuana trade at as much as $7 billion. Instead, the mayors argue the drug could be raising millions in tax revenue for the province when it needs it most.

In an interview Friday, Robertson said that he has seen the impact of criminalizing marijuana on the streets of Vancouver.

"The federal government would do us all a favour by taxing and regulating marijuana, making sure that we have another source of revenue, rather than the expense of having to continually chase gangs who are well-funded by the marijuana industry," he told CTV News.

"It's a big change, and one that needs to be done very thoughtfully, but I think it's a change that could make a big difference in terms of crime, reducing gang activity and ensuring that we can make change that's positive rather than continuing to fight a battle that we can't win."

Before Robertson made his stance known, B.C.'s "Prince of Pot," Marc Emery, who is currently serving a five year prison sentence in the U.S. for selling marijuana seeds to Americans, called the former mayors' support for legalization only mildly encouraging.

"It's hopeful that four former mayors have made crystal clear the urgency and necessity of ending prohibition," Emery wrote in a statement to CTV News. "It remains disturbing that virtually no politician currently in elected office at any level advocates this."

Emery and the mayors argue politicians are falling out of step with the Canadian electorate on the issue of cannabis, an assertion backed up by a growing number of polls and surveys.

An Angus Reid survey released last month found 69 per cent of respondents in favour of taxing and regulation pot over chasing down growers and sellers.

Only 39 per cent supported minimum prison sentences for marijuana-related crime, and a mere 12 per cent said they were in favour of maintaining Canada's current pot laws.

But Sullivan, who held Vancouver's top office from 2005 to 2008, said it's more complicated supporting marijuana legalization as an elected official.

"When you're in office you have a lot people depending on you, and they don't want you to say controversial things," Sullivan said.

By now, however, the mayors' support may be moot. Marijuana laws remain under federal jurisdiction, and softening them isn't on the agenda for Stephen Harper's Conservative majority.

At a Vancouver appearance Friday, Harper told reporters he had no intention of following through on the mayors' recommendations, calling his government "strongly opposed" to drug legalization.

To the contrary, the government's pending omnibus crime bill would toughen drug laws, increasing minimum or maximum prison sentences for various crimes. The jail term for marijuana production would double from seven years to 14.

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