Royal assent is the method by which a monarch formally approves an act of the legislature, either directly or through an official acting on the monarch's behalf. In some jurisdictions, royal assent is equivalent to promulgation, while in others that is a separate step. Under a modern constitutional monarchy, royal assent is considered little more than a formality. Even in nations such as the United Kingdom, Norway, the Netherlands, Liechtenstein and Monaco which still, in theory, permit their monarch to withhold assent to laws, the monarch almost never does so, except in a dire political emergency or on advice of government. While the power to veto by withholding royal assent was once exercised often by European monarchs, such an occurrence has been very rare since the eighteenth century.

Constitutional monarchy, also known as limited monarchy, parliamentary monarchy or democratic monarchy, is a form of monarchy in which the monarch exercises their authority in accordance with a constitution and is not alone in making decisions. Constitutional monarchies differ from absolute monarchies in that they are bound to exercise powers and authorities within limits prescribed by an established legal framework.