Eric Holder just did. From NPR, which broke the news that the Justice Department is seeking to void the corruption conviction against the former Alaska Senator:
With more ugly hearings expected, Holder is said to have decided late Tuesday to pull the plug. His decision is said to be based on Stevens' age — he's 85 — and the fact that Stevens is no longer in the Senate. Perhaps most importantly, Justice Department officials say Holder wants to send a message to prosecutors throughout the department that actions he regards as misconduct will not be tolerated.
"The Department of Justice must always ensure that any case in which it is involved is handled fairly and consistent with its commitment to justice," Holder said in his statement.
This is definitely an embarrassment for DOJ, but it's hard to argue with Holder's rationale. Plus, the fact that the transgressions occurred under a different Attorney General had to make the decision even easier for him.