Ultra vires is a Latin phrase meaning literally "beyond the powers", although its standard legal translation and substitute is "beyond power". If an act requires legal authority and it is done with such authority, it is characterised in law as intra vires (literally "within the powers"; standard legal translation and substitute, "within power"). If it is done without such authority, it is ultra vires. Acts that are intra vires may equivalently be termed "valid" and those that are ultra vires "invalid".
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