Frivolous litigation is the use of legal processes with apparent disregard for the merit of one's own arguments. It includes presenting an argument with reason to know that it would certainly fail, or acting without a basic level of diligence in researching the relevant law and facts. That an argument was lost does not imply the argument was frivolous; a party may present an argument with a low chance of success, so long as it proceeds from applicable law.
Frivolous litigation may be based on absurd legal theories, may involve a superabundance or repetition of motions or additional suits, may be uncivil or harassing to the court, or may claim extreme remedies. A claim or defense may be frivolous because it had no underlying justification in fact, or because it was not presented with an argument for a reasonable extension or reinterpretation of the law. A claim may be deemed frivolous because existing laws unequivocally prohibit such a claim, such as a Good Samaritan law.