Vancouver B.C. April 20, 2014 Big Day to celebrate as thousand gathered in front of Vancouver Art Gallery to take part in the 420 Marijuana smoke in here in Vancouver on April 20, 2014. (Photo by Mark van Manen/PNG Staff Photographer/Ian Austin Province News/Vancouver Sun News & Web stories)

People gather on the lawns of Parliament Hill during the Fill the Hill marijuana rally on Parliament Hill in Ottawa on Sunday, April 20, 2014. (Photo by Justin Tang/The Canadian Press)

Partygoers listen to live music on the second of two days at the annual 4/20 marijuana festival in Denver, Sunday April 20, 2014. The annual event is the first 420 marijuana celebration since retail marijuana stores began selling in January 2014. (Photo by Brennan Linsley/AP Photo)

A man in a bear costume smokes a joint at the Fill the Hill marijuana rally on Parliament Hill in Ottawa on Sunday, April 20, 2014. (Photo by Justin Tang/The Canadian Press)

A woman holds pins supporting the legalization of marijuana at the Fill the Hill marijuana rally on Parliament Hill in Ottawa on Sunday, April 20, 2014. (Photo by Justin Tang/The Canadian Press)

Proponents for the legalisation of cannabis gather in Heaton Park in Manchester for “420 Day”. The event is organised by pro-cannabis groups ManCan and Mannijuana and is one of many taking place in cities across the world on Sunday, 20th April 2014. (Photo by London News Pictures/REX Feature)

Partygoers listen to live music and smoke pot on the second of two days at the annual 4/20 marijuana festival in Denver, Sunday April 20, 2014. The annual event is the first 420 marijuana celebration since retail marijuana stores began selling in January 2014. (Photo by Brennan Linsley/AP Photo)

A woman takes part in a 420 dance party, an event celebrating marijuana culture, at Central Park in New York April 20, 2014. (Photo by Carlo Allegri/Reuters)

People take part in a 420 dance party, an event celebrating marijuana culture, at Central Park in New York April 20, 2014. (Photo by Carlo Allegri/Reuters)

An entrepreneur sells pre-rolled joints during 420 celebrations at Hippie Hill in Golden Gate Park in San Francisco, Calif., on Sunday, April 20, 2014. (Photo by Sarah Rice/AP Photo/San Francisco Chronicle)

With the Colorado state capitol building visible in the background, partygoers dance and smoke pot on the first of two days at the annual 4/20 marijuana festival in Denver, Saturday April 19, 2014. The annual event is the first 420 marijuana celebration since retail marijuana stores began selling in January 2014. (Photo by Brennan Linsley/AP Photo)

Vanessa Vitali plays with a hoop at the annual 4/20 marijuana festival near downtown Denver at Civic Center Park, Saturday, April 19, 2014. The two-day festival, which is expected to draw tens of thousands of people, features music, vendors and speakers in Civic Center Park in front of the state capitol building. (Photo by Brennan Linsley/AP Photo)

Vancouver B.C. April 20, 2014 Big Day to celebrate as thousand gathered in front of Vancouver Art Gallery to take part in the 420 Marijuana smoke in here in Vancouver on April 20, 2014. Here lots of free “joints” ready for the big moment. (Photo by Mark van Manen/PNG Staff Photographer/Ian Austin Province News/Vancouver Sun News & Web stories)