If Fox news is telling lies about the President why doesn't he stop them using defamation law?

If a sitting President of the United States even filed a suit for violation for defamation, it would be a precedent that would clog up the courts for decades, and would be very difficult to prosecute anyway. It would also make him/her petty and insecure, rather like President Nixon and his enemies list. Viewers or listeners should be aware that there is a disclaimer that the stations issue that their management does not necessarily agree with a position and should not be held liable for its presentation. According to the FCC, that's a huge loophole to go along with the freedoms of expressions that we have in this country. If a statement is made, such as when Rep. Wilson referred to Obama as a liar on the house floor, that is just a matter of poor taste and judgment on his part. It is not a violation of law. He was reprimanded by the House and made to apologize to the President and to his peers in the House. There are ways to communicate an opposing view using decorum without ripping someone's integrity to shreds.