Arbitrary, capricious and unreasonable is a legal concept in American jurisprudence.
In the State of New York it is one of the legal grounds under which a government official's official action may be challenged in the state court of law under Article 78 of the Civil Practice Law and Rules, New York State's statutory procedure for such action. It is a concept in this state's administrative law. The formal procedure by which such an action is litigated is known in New York as an "Article 78 proceeding".