LOS ANGELES, CA – SEPTEMBER 7: Marijuana plants grow at Perennial Holistic Wellness Center, a not-for-profit medical marijuana dispensary in operation since 2006, on September 7, 2012 in Los Angeles, California. A group of activists have submitted about 50,000 signatures in an effort to force a referendum on a marijuana dispensary ban in Los Angeles to take effect next week. A minimum of 27,425 valid signatures from registered voters is needed to let voters decide on the issue in March, and until the number can be verified, the ban will not be enforced. . The ban would not prevent patients or cooperatives of two or three people to grow their own in small amounts. Californians voted to legalize medical cannabis use in 1996, clashing with federal drug laws. (Photo by David McNew/Getty Images)