In order for there to be a valid claim for defamation the statement at issue would have to be false. A truthful statement is not defamatory.

However, the problem may arise that the plaintiff does not perceive the statement as truthful, and may initiate the suit anyway. The defendant would have to go to the trouble and expense of defending against the claim.

However, most states have remedies against plaintiff's that inititate frivolous law suits either statutory or at common law. A suit for common law abuse of process is one example. In Connecticut we have a statutory protection of a suit for vexatious litigation, which allows the defendant to recover double, possibly tripple damages and attorney's fees. The drawback is that the suit for vexatious litigation can not be asserted by a counterclaim. The original suit for defamation must first end in a judgment for the defendant. Once the plaintiff in the defamation suit has lost, he is subject to the defendant's subsequent suit for vexatious litigation...and a heavy award of damages.