Ultra vires is a Latin phrase that literally means "beyond the power." Its inverse is called intra vires, meaning "within the power".

It is used as a legal term in a number of contexts:

• In corporate law, ultra vires describes acts attempted by a corporation that are beyond the scope of powers granted by the corporation's charter, the laws authorizing its formation, or similar founding documents. Acts attempted by a corporation that are beyond the scope of is charter are void or voidable. Except in the case of non-profit corporations (including municipal corporations), this legal doctrine is obsolescent; within recent years, almost all business corporations are chartered to allow them to transact any lawful business. The doctrine still has have some life among non-profit corporations or state-created corporate bodies established for a specific public purpose, like universities or charities. In some jurisdictions, such as Australia, legislation provides that a corporation has all the powers of a natural person plus others; also, the validity of acts which are made ultra vires is preserved.

• Under constitutional law, particularly in Canada and the United States, constitutions give federal and provincial or state governments various powers. To go outside those powers would be ultra vires; for example, although the court did not use the term, in striking down a federal law in United States v. Lopez on the grounds that it exceeded the Constitutional authority of Congress, the Supreme Court effectively declared the law to be ultra vires.

• In British constitutional law, ultra vires describes patents, ordinances and the like enacted under the prerogative powers of the Crown that contradict statutes enacted by the King-in-Parliament. Almost unheard of in modern times, ultra vires acts by the Crown or its servants were previously a major threat to the rule of law.

• In administrative law, an act may be judicially reviewable ultra vires in a narrow or broad sense. Narrow ultra vires applies if an administrator did not have the substantive power to make a decision or it was wrought with procedural defects. Broad ultra vires applies if there is an abuse of power (e.g. Wednesbury unreasonableness or bad faith) or a failure to exercise an administrative discretion (e.g. acting at the behest of another or unlawfully applying a government policy). Either doctrine may entitle a claimant to various prerogative writs, equitable remedies or statutory orders if they are satisfied.

Latin legal phrases