Prerogative powers are those which are at the autonomous disposal of heads of state and which do not require sanction by a legislature. Their theoretical justification lies in Locke's view of a need for a final arbiter to maintain order. In liberal democracies written constitutions vary in their definition of prerogative powers for heads of state. Constitutional monarchs and some presidents, for example in Germany, have almost entirely ceremonial powers, although in some cases, such as the Spanish monarchy under King Juan Carlos, important political roles can be played. More conventionally, presidents have reserve or emergency powers to be used in situations of political crisis, although by definition they are rarely invoked. In the United States, the President as head of state has considerable powers beyond those in an emergency which relate to the initiation of legislation, maintenance of internal order, diplomatic relations, and the command of the armed forces. In theory the Presidency is checked by Congress, federalism, and an independent judiciary, but in practice has asserted considerable autonomy in the use of such powers. The French Presidency in the Fifth Republic has perhaps the most extensive constitutionally defined prerogative powers. In addition to unconstrained emergency powers the French President ordinarily has the right to chair the council of ministers, with the power to appoint, rather then merely nominate, and dismiss the prime minister, negotiate with foreign powers, and call referendums. This effectively makes the President the head of the government as well as head of state. In the United Kingdom in the absence of a written constitution prerogative powers have become discretionary powers of the political executive, carried out in the name of the monarch. These cover the making of foreign policy, the prosecution of war, and the making of appointments to the armed forces and the central machinery of government. In these policy areas, whilst still open to scrutiny, the UK executive is considerably more autonomous from parliamentary decision‐making processes than executives in other Westminster‐style systems, although the controversy over the decision to go to war in Iraq in 2003 led to proposals in 2008 for any such final decision in future to be made by Parliament.