The Mayor of San Diego is encouraging jurors of an upcoming medical marijuana case to reject the prosecution’s argument, which rests on the fact that marijuana is banned at the federal level. The feds arrested Ronnie Chang of San Marcos in 2009 for operating a medical marijuana dispensary. He is just one of the many Californians who have faced legal consequences for their state-sanctioned efforts to bring relief to patients. [caption id="attachment_6451" align="alignright" width="210"] Mayor Bob…