He does not have to. There are certain types of defamation which are considered "per se libel" or "per se slander". He doesn't have to prove anything other th

He does not have to. There are certain types of defamation which are considered "per se libel" or "per se slander". He doesn't have to prove anything other than that you made the statement--you would have to prove the statement is true. Moreover, per se defamation does not require proof of damages; the very act of the defamation is damage enough.