The self-proclaimed “guru of ganja” was convicted again Wednesday in federal court of illegally growing hundreds of marijuana plants that he said were meant to treat sick people, which California law allows.

Ed Rosenthal was convicted after U.S. District Judge Charles Breyer prohibited the marijuana activist’s lawyers from telling the jury he was working for a pot club sanctioned by Oakland government officials. The decision underscored the tension between federal law, which prohibits marijuana, and laws in 11 states that have legalized pot for medical purposes.