On Fox News Sunday today, Rod Rosenstein said that Robert Mueller has to come back to him for authorization if he wants to expand the investigation beyond Russia. But Mueller’s original mandate was so broad and vague there is surely an awful lot that can fit under it. As Andy McCarthy has written repeatedly and persuasively, Rosenstein should have been specific about what alleged crimes Mueller was charged with investigating, and then the order could have been updated and expanded if Mueller made a compelling case for doing so. This would have 1) provided some transparency about — and control over — what exactly Mueller is investigating; 2) allowed Rosenstein to squelch any fishing expedition before it got started. As it is now, Trump may fire Mueller over a fishing expedition that may or may not exist.