U.S. EPA's new chief of staff doesn't scare easily. Gwen Keyes Fleming is a former district attorney who's gone nose to nose in the courtroom with accused murderers, drug dealers, corrupt officials and other bad guys. "Being up against an opponent in a courtroom and being on for the length of a trial, you do build a certain stamina," Keyes Fleming said. "You just get in the ring and do your best job to prove your case." Now Keyes Fleming is taking on all comers for EPA.