In law, frivolous or vexatious is a term used to challenge a complaint or a legal proceeding being heard as lacking in merit, or to deny, dismiss or strike out any ensuing judicial or non-judicial processes.
While the term is referenced in laws and regulations, it is often not defined by statute, being developed instead by decisions of the courts.
One case was Keaveney v. Geraghty,[3] where the plaintiff's libel proceedings were stayed on the grounds that they were, inter alia, frivolous, vexatious, and "an abuse of the process of the Court".
A case is frivolous if it has no reasonable chance of succeeding, and is vexatious if it would bring hardship on the opposite party to defend against an unnecessary and inevitably unsuccessful claim.
For example, the Data Protection Commissioner shall investigate any complaint made to him about the contravention of the Data Protection Acts unless he is of the opinion that it is frivolous or vexatious[5] and the head of a government department may refuse access to records under the Freedom of Information Act if the request is frivolous or vexatious.