The duty to share exculpatory evidence with the defense is not a gray area. In the words of one former U.S. attorney: “It's Prosecution 101.” So the revelation of withheld evidence that led to the dismissal of former Sen. Ted Stevens' corruption conviction has not just further tarnished the Justice Department, it has left former prosecutors shaking their heads in dismay.

“It was quite disappointing,” says Wendy Wysong, a partner at Clifford Chance and a former assistant U.S. attorney in the District of Columbia. “As a former prosecutor, I sympathize with the prosecutors in the sense that obviously they were taken by surprise that the case went to trial so quickly. On the other hand, we're trained to never indict until we're ready to go to trial.”

The high-profile prosecutorial misconduct cast another shadow over the department, just as it works to gain distance from Bush-era controversies and establish a new culture under Attorney General Eric Holder.