Latin meaning act without authority or literally beyond powers. This term is frequently used in business and agency law the Doctrine of Ultra Vires. An ultra virus act occurs when one commits an act that is beyond the powers or purpose of a corporation, e.g. the commingling of the assets of a wholly owned corporation with the sole shareholder’s personal assets. In such an instance, this ultra vires act allows creditors of the corporation to pierce the corporate veil and sue the shareholder personally as if he was the corporation. Personal assets may then be seized and subject to the debt of the corporation.