Medical marijuana advocates in San Diego have unveiled a proposed ballot measure to end the current municipal crackdown on dispensaries. The proposed initiative would set a 2.5% sales tax for the storefront dispensaries and prohibit them within 600 feet of schools and playgrounds, as well as laying out security and inspection requirements. "Our intent is to bring back safe access to medical cannabis for qualified patients," said Jessica McElfresh of the Patient Care Association of California, which helped draft the proposal. "Voters have almost always overwhelmingly supported medical marijuana responsible regulation." Proponents need to collect about 62,000 voter signatures to qualify the measure for the 2012 November ballot.