Lawyers for the city of Atlanta on Thursday asked a federal appeals court to overturn a lower court ruling that let nonresidents collect signatures as part of the “Stop Cop City” effort to force a referendum on a police and fire training center. If the city wins, the 11th U.S. Circuit Court of Appeals could kill the petition drive by ruling it illegal under state law, or rule all of 100,000-plus signatures collected are void because none were submitted by the original 60-day deadline of Aug. 21.