An order of succession is a formula or algorithm that determines who inherits an office upon the death, resignation, or removal of its current occupant.

Monarchies

In hereditary monarchies the order of succession is followed in order to determine who becomes the new monarch when the old monarch dies or vacates the throne. Such orders of succession generally specify which descendant of the previous monarch, or in default of a direct heir, which sibling or collateral of the previous monarch, will assume the throne. Generally, the line of succession is restricted to persons of the blood royal (see morganatic marriage), that is to those born into or descended from the present royal family or a previous sovereign. The persons in line to succeed to the throne are called "dynasts." Constitutions, statutes, house laws, and norms may regulate the number of dynasts and the qualifications of potential successors to the throne.

Different monarchies use different algorithms or formulas to determine the line of succession. Chief among the lineal mechanisms are:

Salic Law

Salic Law (also called Agnatic Succession) is the complete exclusion of females of the dynasty and their descendants from the succession. The Salic Law applied to the former royal or imperial houses of Albania, France, Italy, Korea, Romania, Yugoslavia, and Prussia/German Empire. It currently applies to the royal or imperial houses of Japan, Jordan, and Nepal. Generally, hereditary monarchies that operate under the Salic Law also use primogeniture among male descendants in the male line to determine the rightful successor.

Semi-Salic Law

According to the FAQ for the newsgroup alt.talk.royalty, under semi-Salic law, "the succession is reserved firstly to all the male dynastic descendants of all the eligible branches by order of primogeniture, then upon total extinction of these male descendants to the eldest of the dynastic female descendants." Current monarchies that operated under Semi-Salic law include Luxembourg and Liechtenstein. Former monarchies that operated under semi-Salic law included Austria (later Austria-Hungary), Bavaria, Hanover, Württemberg, Russia, Saxony, Tuscany, and the Kingdom of the Two Sicilies. However, note that if a female descendant should take the throne, she will not necessarily be the closest relative in relation to the current monarch. For instance, let's say Prince X is elder than Prince Y. Prince X becomes King X, then dies with only a daughter, Princess X, so Prince Y becomes King Y. King Y has a daughter, Princess Y, and then King Y dies, and there are no more male heirs. Though Princess Y is the current king's eldest daughter, her cousin, Princess X, is more senior, and thus the latter would become Queen X.

Primogeniture

Primogeniture (or more properly Male Primogeniture) is a mechanism whereby male descendants of the sovereign take precedence over female descendants, with children representing their deceased ancestors, and where the senior line of descent always takes precedence over the junior line, in each gender. Elder sons always take precedence over younger sons. Younger sons always take precedence over older daughters. The right of succession always belongs to the eldest son of the reigning sovereign (see heir apparent), and then to the eldest son of the eldest son. This is the system in Britain, Spain (since 1978), Denmark, and Monaco.

Cognatic Primogeniture

Cognatic Primogeniture (or Absolute Primogeniture) is a law in which the eldest child of the sovereign succeeds to the throne, regardless of gender, and where females (and their descendants) enjoy the same right of succession as males. This is currently the system in Belgium, the Netherlands, Norway, and Sweden.

See also: crown prince, monarchy, prince, Royal House, royal family, Line of Succession to the British Throne, Order of precedence.

Government

In politics, a desire to ensure a continuity of operations at all times has resulted in most offices, no matter how bureaucratic, having some formalized order of succession.

In republics with fixed-term elections, the national president is sometimes succeeded following death or resignation by the vice president, in turn followed by various office holders of the parliament or congress, and then members of the cabinet. For example, if both the President of the United States and Vice President of the United States are unable to serve, the Speaker of the United States House of Representatives takes over as President. Next in line is the President pro tempore of the United States Senate, who is followed by the Secretary of State, and other cabinet officials. In many republics, however, a new election takes place some period after the demise of the incumbent president.

See also: continuity of government, United States presidential line of succession