Lawyer Daniel B. Evans writes:
[W]hen a judge calls an argument "ridiculous" or "frivolous," it is absolutely the worst thing the judge could say. It means that the person arguing the case has absolutely no idea of what he is doing, and has completely wasted everyone's time. It doesn't mean that the case wasn't well argued, or that judge simply decided for the other side, it means that there was no other side. The argument was absolutely, positively, incompetent. The judge is not telling you that you that you were "wrong." The judge is telling you that you are out of your mind.
Litigants who represent themselves (in forma pauperis and pro se) often make frivolous arguments due to their limited knowledge of the law and procedure. The particular tendency of prisoners to bring baseless lawsuits led Congress to pass and Bill Clinton to sign the Prison Litigation Reform Act, which strictly limits the ability of prisoners to bring actions.
The more common use of the term "frivolous" in political discourse refers to lawsuits that are based on a theory that seems absurd, where there is no link between the conduct of the defendant and the injuries sustained by the plaintiff, or where the claim or result in damages greatly exceed what one would expect from a brief summary of the case. Awards for medical malpractice are also frequently derided as frivolous. In these cases a jury and a judge decided in favor of the plaintiff; the plaintiff's claim was therefore technically not frivolous, though it might be considered frivolous colloquially. Because of the ambiguity in the term, calling these lawsuits "frivolous" can lead to confusion because opposite sides of the tort reform debate can both say they oppose "frivolous" suits, with the tort reform supporters referring to the colloquial understanding, and tort reform opponents referring to the narrower technical definition.