Reserve power

In a parliamentary or semi-presidential system of government, a reserve power is a power that may be exercised by the head of state without the approval of another branch of the government. Unlike in a presidential system of government, the head of state is generally constrained by the cabinet or the legislature in a parliamentary system, and most reserve powers are usable only in certain exceptional circumstances. In some countries, reserve powers go by another name; for instance, the reserve powers of the President of Ireland are called discretionary powers.

Constitutional monarchies

In monarchies with either an uncodified or partly unwritten constitution (such as the United Kingdom or Canada) or a wholly written constitution that consists of a text augmented by additional conventions, traditions, letters patent, etc. (such as Australia), the monarch generally possesses reserve powers.

Typically these powers are: to grant pardon; to dismiss a prime minister; to refuse to dissolve parliament; and to refuse or delay royal assent to legislation (to withhold royal assent amounts to a veto of a bill, while to reserve royal assent in effect amounts to a decision to neither grant nor refuse assent, but to delay taking a decision for an undetermined period). There are usually strict constitutional conventions concerning when these powers may be used, and these conventions are enforced by public pressure. Using these powers in contravention of tradition would generally provoke a constitutional crisis.