Operators of Fairfax’s Marin Alliance for Medical Marijuana moved this week to prevent a federal mandate that it close its doors and remove all trace of the substance by November 21. The order is part of a national crackdown on marijuana growers and licensed dispensaries, which prosecutors believe often mask large-scale illegal activity. Marin Alliance founder Lynette Shaw called the sweeps unprecedented and completely unfounded. “We have never violated any rules or any laws. We’ve…