Definition of ultra vires in US English:

ultra vires

adverb & adjective

  • Beyond one's legal power or authority.

    as adjective ‘jurisdictional errors render the decision ultra vires’
    • ‘As a result, a taxpayer who has made a payment pursuant to ultra vires legislation has a right to restitution.’
    • ‘It is not suggested that Byelaw 20 was itself ultra vires the powers which the primary legislation conferred upon the British Railways Board.’
    • ‘This lesson provides an overview of the historical significance of the ultra vires doctrine, its subsequent decline in importance, and its modern status.’
    • ‘Delegated legislation is also subject to control by the courts whose judges can declare a piece of delegated legislation to be ultra vires.’
    • ‘An ultra vires act is one beyond the purposes or powers of a corporation.’


Latin, literally ‘beyond the powers’.


ultra vires

/ˌəltrə ˈvaɪriz//ˌəltrə ˈvīrēz/