epa01803190 Oaksterdam University, Chris McCatheran, horticulturalist clips leaves off stems during harvesting of buds from medical marijuana plants being grown at the Oaksterdam University in Oakland, California, USA, 22 July 2009, the day after Oakland residents overwhelmingly voted on 21 July to approve a first-of-its kind tax on medical marijuana sold at the city’s four cannabis dispensaries. Oaksterdam University is a trade school for budding medical marijuana dispensary workers. State tax authorities last week released an estimate that California could raise 1.4 billion dollars with a cannabis levy. The Los Angeles City Council proposed a medical marijuana tax earlier this month, and the cities of Berkeley and San Francisco may consider similar legislation. EPA/PETER DASILVA .