Constitutional Models

In protocol terms, states are distinguished as monarchy or republic depending on the style (and usually mode of accession, see below) of their head of state, a typical constitutional provision, but as such this is not defining for the actual political system, which often evolves significantly, or can remain unaltered in other respects despite a transition from monarchy to republic (or, rarer, vice versa).

Different state constitutions (fundamental laws) establish different political systems, but four major types of heads of state can be distinguished:

The non-executive head of state system, in which the head of state does not hold any executive power and mainly plays a symbolic role on behalf of the state;

The parliamentary system, in which the head of state possesses executive power but the exercise of this power is done on the advice of a cabinet;

The semi-presidential system, in which the head of state shares exercise with a head of government; and

The presidential system, in which the head of state is also the head of government and actively exercises executive power.

Non-Executive Head of State

Two contemporary figurehead monarchs who do not even in theory possess any discretionary governance powers: Akihito, Emperor of Japan (left), and Carl XVI Gustaf, King of Sweden (right.)

These officials are excluded completely from the executive: they do not possess even theoretical executive powers or any role, even formal, within the government. Hence their states' governments are not referred to by the traditional parliamentary model head of state styles of "His/Her Majesty's Government" or "His/Her Excellency's Government." Within this general category, variants in terms of powers and functions may exist.

Since the passage of the Instrument of Government of 1974, Swedish kings no longer have many of the usual parliamentary system head of state functions that had previously belonged to them. The Speaker of the Riksdag appoints (following a vote in the Riksdag) the Prime Minister and terminates his commission following a vote of no confidence or voluntary resignation. Cabinet members are appointed and dismissed at the sole discretion of the Prime Minister. Executive authority is vested in the Government (i.e. cabinet, of which the King is not a member). Laws and ordinances are promulgated by two cabinet members in unison "On Behalf of the Government". The remaining constitutional functions of the Monarch are to open the annual session of the Riksdag, to chair the foreign advisory committee, to preside at the special cabinet council when a new Prime Minister takes office, and to be kept informed by the Prime Minister on matters of state.

In contrast, the only contact the Irish president has with the Irish government is through a formal briefing session given by the Taoiseach (prime minister) to the President. However, he or she has no access to documentation and all access to ministers goes through the Department of the Taoiseach (prime minister's office). The President does however hold reserve powers, such as referring a bill to the Supreme Court to test its constitutionality, which are used under the president's discretion.