Partygoers listen to live music and smoke pot on day two of the annual 420 Rally in Denver on Sunday, April 20, 2014. <a href="index.php?page=&url=http%3A%2F%2Fwww.cnn.com%2F2013%2F04%2F20%2Fopinion%2Freiman-marijuana-day%2F" target="_blank">420 is a once clandestine term used in pot culture to refer to marijuana. </a>
Celebrating 420 —
Partygoers listen to live music and smoke pot on day two of the annual 420 Rally in Denver on Sunday, April 20, 2014. 420 is a once clandestine term used in pot culture to refer to marijuana.
Brennan Linsley/AP
Fans react to the MTHDS as they preform during the 420 Rally in Denver's Civic Center Park on April 20.
Celebrating 420 —
Fans react to the MTHDS as they preform during the 420 Rally in Denver's Civic Center Park on April 20.
Joe Amon/The Denver Post/Getty Images
Marijuana smoke fills the air at 4:20 p.m. in Civic Center Park in Denver on April 20.
Celebrating 420 —
Marijuana smoke fills the air at 4:20 p.m. in Civic Center Park in Denver on April 20.
Joe Amon/The Denver Post/Getty Images
Partygoers listen to live music and smoke pot at Denver's 420 Rally on April 20.
Celebrating 420 —
Partygoers listen to live music and smoke pot at Denver's 420 Rally on April 20.
Brennan Linsley/AP
Ryme Windham smokes marijuana at 4:20 pm outside at Hempfest on April 20 in Seattle. Seattle Hempfest is an annual event for the purpose of educating the public about the benefits of marijuana and advocating for its decriminalization.
Celebrating 420 —
Ryme Windham smokes marijuana at 4:20 pm outside at Hempfest on April 20 in Seattle. Seattle Hempfest is an annual event for the purpose of educating the public about the benefits of marijuana and advocating for its decriminalization.
Meg Roussos/Getty Images
John the Freak teaches a joint rolling class at Seattle's Hempfest on April 20.
Celebrating 420 —
John the Freak teaches a joint rolling class at Seattle's Hempfest on April 20.
Meg Roussos/Getty Images)
Attendees look at glass pipes used for smoking marijuana being sold at Hempfest on April 20 in Seattle.
Celebrating 420 —
Attendees look at glass pipes used for smoking marijuana being sold at Hempfest on April 20 in Seattle.
Meg Roussos/Getty Images
A young woman smokes marijuana during a demonstration calling for cannabis to be legalized at a 420 Day event in Hyde Park in London on Sunday, April 20.
Celebrating 420 —
A young woman smokes marijuana during a demonstration calling for cannabis to be legalized at a 420 Day event in Hyde Park in London on Sunday, April 20.
ANDY RAIN/EPA
British police look on as a cloud of smoke rises over protesters in London's Hyde Park.
Celebrating 420 —
British police look on as a cloud of smoke rises over protesters in London's Hyde Park.
ANDY RAIN/EPA/Landov
People gather on the lawns of Parliament Hill on April 20 during the Fill the Hill marijuana rally in Ottawa, Canada.
Celebrating 420 —
People gather on the lawns of Parliament Hill on April 20 during the Fill the Hill marijuana rally in Ottawa, Canada.
Justin Tang/The Canadian Press/AP
A man in a bear costume smokes a joint on April 20 at the Fill the Hill marijuana rally on Parliament Hill in Ottawa.
Celebrating 420 —
A man in a bear costume smokes a joint on April 20 at the Fill the Hill marijuana rally on Parliament Hill in Ottawa.
Justin Tang/The Canadian Press/AP
People gather on the lawns of Parliament Hill during the Fill the Hill marijuana rally in Ottawa on April 20.
Celebrating 420 —
People gather on the lawns of Parliament Hill during the Fill the Hill marijuana rally in Ottawa on April 20.
Justin Tang/The Canadian Press/AP
Ed Forchion, a pro-marijuana activist known as NJ Weedman, carries a large cross with huge likeness of a marijuana leaf on April 20 as he walks in front of the New Jersey Statehouse in Trenton, New Jersey. Dozens of activists and community members gathered in front of Statehouse to show their support for legalizing marijuana.
Celebrating 420 —
Ed Forchion, a pro-marijuana activist known as NJ Weedman, carries a large cross with huge likeness of a marijuana leaf on April 20 as he walks in front of the New Jersey Statehouse in Trenton, New Jersey. Dozens of activists and community members gathered in front of Statehouse to show their support for legalizing marijuana.
Mel Evans/AP
Partygoers dance and smoke pot on the first of two days of The Official 420 Rally annual marijuana festival in Denver on Saturday, April 19. This is the first year of the festival where it has been legal to sell marijuana for recreational use in Colorado.
Celebrating 420 —
Partygoers dance and smoke pot on the first of two days of The Official 420 Rally annual marijuana festival in Denver on Saturday, April 19. This is the first year of the festival where it has been legal to sell marijuana for recreational use in Colorado.
Brennan Linsley/Brennan Linsley
Sarah Rader of Colorado Springs hula-hoops in Civic Center Park in Denver on April 19.
Celebrating 420 —
Sarah Rader of Colorado Springs hula-hoops in Civic Center Park in Denver on April 19.
Hyoung Chang/The Denver Post/Getty Images
Zion I performs at Denver's festival on April 19.
Celebrating 420 —
Zion I performs at Denver's festival on April 19.
Brennan Linsley/AP
"Chaz" shows off his marijuana themed hat in Denver on April 19.
Celebrating 420 —
"Chaz" shows off his marijuana themed hat in Denver on April 19.
Seth McConnell/The Denver Post/Getty Images
Police officers on bikes patrol Denver's Civic Center Park on April 19, the first day of the festival.
Celebrating 420 —
Police officers on bikes patrol Denver's Civic Center Park on April 19, the first day of the festival.
Brennan Linsley/AP
Partygoers listen to live music on April 19.
Celebrating 420 —
Partygoers listen to live music on April 19.
Brennan Linsley
Denver hip-hop duo Bass Physics performs at Civic Center Park in Denver on April 19.
Celebrating 420 —
Denver hip-hop duo Bass Physics performs at Civic Center Park in Denver on April 19.
Brennan Linsley/AP
A glittery pot leaf adorns the cheek of an attendee in Denver on April 19.
Celebrating 420 —
A glittery pot leaf adorns the cheek of an attendee in Denver on April 19.
Seth McConnell/The Denver Post /Getty Images