When former reality television contestant Summer Zervos accused Donald Trump of sexual misconduct last fall, she pursued her claims solely in the court of public opinion, since the allegations dated too far back to allow a lawsuit.

But last month, she found a fresh approach to fight the former host of "The Apprentice," who has vehemently denied her allegations that he groped her in 2007. By professing his innocence, the man who is now president of the United States had effectively called her a liar, Servos alleges in a defamation lawsuit.

The suit copied a rare legal tactic employed most notably by several women who have accused the actor and comedian Bill Cosby of sexual assault: using his denials as the basis for a defamation claim.