A washington post article says:

Waterboarding, [Mukasey] told the House committee, “cannot possibly be the subject of . . . a Justice Department investigation” because its use was approved by the Justice Department’s Office of Legal Counsel. Mukasey made a parallel argument about the National Security Agency’s warrantless wiretapping program, saying the Justice Department could not investigate that program because it was approved at the outset by the department’s lawyers.

… a loophole so large that anything at all can fit through it?