lucy24 - 7:15 pm on Aug 27, 2013 (gmt 0)
Are you really asking "Can he sue me?" or "Can he win?"
In the US, the answer to the first is: Yes, unless the would-be plaintiff has an existing court order requiring pre-approval of all submitted suits. (This is extremely rare, arising from situations like a successful "abuse of process" suit file by someone else.) By itself this can be either a minor inconvenience or a major expense depending on what level of court it's filed in. For a superior court ("Supreme Court" in New York state) of course they'd have to convince a lawyer to take their case.
In all places, the answer to the second is: Talk to an attorney ;)