A federal appeals court on Thursday ordered the judge handling the criminal case of President Donald Trump’s former national security advisor, Michael Flynn, to respond to a request by Flynn’s lawyers to dismiss the case. The order came two days after Flynn’s lawyers asked the U.S. Circuit Court of Appeals for the District of Columbia to drop the case and assign any future court proceedings to another judge. The Department of Justice two weeks earlier made the surprise move to abandon its own prosecution of Flynn, who had pleaded guilty to lying to the FBI about his conversations with then-Russian...