Ultra Vires

Ultra vires describes an act performed by an entity or official that exceeds the scope of authority granted by law, charter, or governing instrument. In corporate law, an ultra vires act is one that falls outside the purposes or powers defined in the corporation's articles of incorporation, though modern statutes have largely eliminated this defense for third parties who dealt with the corporation in good faith. In administrative and constitutional law, ultra vires refers to government action that exceeds the statutory or constitutional authority delegated to the acting body or official, rendering such action void or voidable.

The ultra vires doctrine remains significant in administrative law, where courts review whether agencies have acted within their statutory mandates. In municipal law, local governments that exceed their delegated powers may have their ordinances struck down as ultra vires, and the doctrine is also applied in challenges to the authority of international organizations.