Membership in unions is on the decline. The Bureau of Labor Statistics reports that the number of unionized workers dropped by 771,000 in 2009, largely reflecting the overall drop in employment due to the recession. With hopes for the passing of the Employee Free Choice Act on the wane, unions have to look elsewhere to boost membership. "We’ve had our problems so we’ve had to diversify," said Marty Frates, secretary-treasurer of Teamsters Local 70 in California, to The Wall Street Journal on the addition of 40 or so employees of an Oakland, California, marijuana-growing company as new Teamsters members. (Medicinal-marijuana use is permitted under California law and dispensaries are common in the state.)

The Teamsters is not the first to see opportunities in marijuana in California. United Food and Commercial Workers (UFCW) represents workers at California’s Oaksterdam University, where students go to learn how to be pot entrepreneurs.

The Service Employees International Union, the largest labor union in California, has endorsed the California ballot initiative (Proposition 19) that seeks to allow those at least 21 years of age to grow and possess marijuana in the state. Union President Bill A. Lloyd reportedly wrote to the pro-legalization campaign that the union "look[s] forward to joining you in any way we can to help pass Proposition 19." Other California labor unions that have come out in support of Proposition 19 include the UFCW, the International Longshore and Warehouse Union, and the Communications Workers of America.