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A woman passes a joint at a pro-marijuana "4/20" celebration in front of the state capitol building April 20, 2010 in Denver, Colorado. Colorado, one of 14 states to allow use of medical marijuana, has experienced an explosion in marijuana dispensaries, trade shows and related businesses in the last year as marijuana use has become more mainstream.
While it's been nearly six months since Colorado and Washington legalized marijuana, each state is still trying to figure out how to regulate the new industry. There are rumblings that Colorado lawmakers might try to make pot illegal again, and in Washington they're still trying to establish ground rules.
To do that, the state's liquor board has hired a team of consultants to figure out how to write regulations for the new legal marijuana industry. One of those people is Mark Kleiman, a UCLA professor and author of "Drugs and Drug Policy: What Everyone Needs To Know."