The U.S. Justice Department has stepped into a rare fight over the authority to regulate government lawyers, backing a former federal prosecutor in Washington who is accused of intentionally keeping evidence secret in a shooting case a decade ago.

Lawyers at Main Justice and the U.S. Attorney’s Office for the District of Columbia teamed up to urge the District of Columbia Board on Professional Responsibility to throw out an ethics committee’s conclusion that a former assistant U.S. attorney, Andrew Kline, violated a D.C. criminal discovery rule. Kline, whose career included a stint at the White House, is now deputy general counsel for global policy at The Go Daddy Group Inc., the Web hosting and domain name registration company.