Of course this all falls apart when the antagonist doesn't have anything left to loose, perhaps because he/she, has lost it all to the aggrieved. The whole thing then reverts to "Sods Law" of which I have written some papers and amendments.
A question: (Something I have no intent to act on). If somebody has details of your identity that was obtained via any source that can be proved, and that person then makes defamatory comment to your PPRune identity, is that a basis for action against them?