Vexatious litigation is legal action which is brought, regardless of its merits, solely to harass or subdue an adversary. It may take the form of a primary frivolous lawsuit or may be the repetitive, burdensome, and unwarranted filing of meritless motions in a matter which is otherwise a meritorious cause of action. Filing vexatious litigation is considered an abuse of the judicial process and may result in sanctions against the offender.
A single action, even a frivolous one, is not enough to raise a litigant to the level of being declared vexatious, though repeated and severe instances by a single lawyer or firm can result in eventual disbarment.
Some jurisdictions have a list of vexatious litigants: people who have repeatedly abused the legal system. Because lawyers could be disbarred for participating in the abuse, vexatious litigants are often unable to retain legal counsel, and therefore represent themselves in court.[1] Those on the list are usually either forbidden from any further legal action or required to obtain prior permission from a senior judge before taking any legal action. The process by which a person is added to the list varies among jurisdictions.