Has the Bush Administration Taken Presidential Power Too Far?

If Bill Clinton's impeachment was a curb on the excesses of the executive branch, it didn't last long. Even some Republicans concede that George W. Bush claimed unprecedented presidential authority, which may have led to violations of law. Now some constitutional lawyers advocate high-level prosecutions for torturing prisoners, spying without warrants, and denying American citizens basic rights.  Are such trials needed to re-establish the rule of law or is it better to move on?