Baltimore’s top prosecutor has filed a rarely used legal petition intended to vacate 3,778 convictions for possession of marijuana, arguing an extraordinary legal strategy is necessary to “right an extraordinary wrong.” In a highly unusual “Maryland v. Maryland” filing in state court, State’s Attorney Marilyn Mosby used a petition called “writ of error coram nobis” that allows a court to reopen cases when substantial error is found that wasn’t apparent in initial judgments. The petition, if granted, could wipe out thousands of pot possession convictions. Mosby’s arguments are based on what she paints as an opportunity to achieve retroactive justice...