In article 1.3 the 1978 Spanish constitution describes the Spanish State as a Parliamentary Monarchy. The Spanish state form is based upon the Montesquian trias politica system that separates the legislative, executive and judicial power. As in most European democracies these powers are represented by a parliament, a government, and a judiciary, each of which are supposed to be independent in their mutual relations. Additionally there is a regional layer of government represented by the autonomous communities. However, apart from the regional and central division, the separation of powers is not clearly arranged in the constitution. Illustrative to this is the integration of the legislature and executive through the government, which is also allowed to propose laws (art. 87.1SC). As such, the executive clearly is the most precedent power, especially embodied in a strong prime minister. Nevertheless, article 1.2SC states that all powers of the state derive from the national sovereign Spanish people. In other words, it derives from parliament representing the people. According to P. Heywood the relation between executive and parliament is not coincidental as the Spanish constituents deliberately sought after a strong and stable executive after the Franco dictatorship. The relation between parliament and government is not rigid either. Since the coming to be of the 1978 constitution, the executive seems to have gotten more dominant, whereas parliament and especially the Senate is regarded to have gotten weaker. This appears to have been especially the result of the absolute parliamentary majorities obtained by previous governments. However, this pattern has come to an end since the current 1996 government and its predecessor came in charge through the support of regional parties. As a result, the autonomous communities seem to be getting more influence on the core executive.
In contrast to the Franco regime, which consisted of only one chamber, the 1978 constitution has established a bi-cameral parliament with a Congress and a Senate. These so-called Cortes Generales, whose function, composition and relation to other state institutions is outlined in the sections III and V SC, represent the Spanish people.
Both houses can hold office for a period of up to four years. Up to now, elections for Senate and Congress have been held simultaneously. However, this is not obliged as either house can be dissolved separately, something which until now has not yet occurred (art.115.1SC). Intermediate periods between the dissolution of the old and installation of the new house and periods in which the houses are not in session are being bridged by the so-called Diputación Permanente which is present in each of the houses(art.78SC). These committees are headed by the presidents of the respective houses and exist of at least 21 members which represent the parliamentary groups. The rights, restrictions and duties of the deputies and the senators are laid down in the constitution and complemented in the standing orders of the respective houses which are both quite similar (art.71&72SC).Congressional membership is incompatible with senatorship and vice versa. Deputies are furthermore excluded from membership of regional assemblies. This exclusion does of course not apply to senators. Other exceptions to parliamentary membership are posed in article 70SC.
In some rare cases both houses meet in joint sessions, e.g. at the inauguration of the king, or to authorise the king to declare a state of war or peace (art.63.3SC). When working together, the president of Congress presides over their joint sessions, illustrating the Congressional precedence.
Each house is presided by a council, the so-called mesa, which is composed of either deputies or senators relevant to the house and consist of a president, a vice-president and secretaries. They are furthermore assisted by special legal advisors. The councils manage and organise the work in each house.
The respective presidents head the mesa and regulate the everyday running of the houses. They are furthermore concerned with a few constitutional duties like the proposal of a new candidate P.M. and the calling of new elections (art.99SC). Both houses furthermore contain a secretariat which provides all parliamentary bodies with legal and administrative assistance.
Both houses are free to draw up their own standing orders and approve their budget. In order to take decisions there must be at least an absolute majority of the members present (art.79.2SC). The members are also under strict control. They are not even allowed to switch parties, but must join the Mixed Committee if they want to leave their own party. Obliged attendance does not only apply to both houses but also to the members of the parliamentary committees. The latter play a crucial part in the legislative duty of parliament, as only these committees may introduce legislation. These committees are either permanent or ad hoc and consist of a proportioned representation of either senators or deputies and in some cases both. The permanent committees are divided into either legislative or non-legislative committees. The legislative committees introduce, examine, amend, and approve draft laws with the exception of constitutional revisions, international affairs, organic laws, basic laws, and the general state budgets (art.75.3SC).The non-legislative committees deal with the internal affairs of the houses and external bodies and organisations. The ad hoc committees can be created by each of the houses or both in order to investigate any subject that is of public interest (art.76.1SC). A recent example of this is the gal ad hoc committee which investigates the involvement of the P.M.’s and other government members in the assassination teams which killed E.T.A terrorists in the late eighties. In practice this form of parliamentary control is used only seldom. The emphasis on these parliamentary committees was not unintentional, as parliament was designed to serve as a well balanced chamber in which the various political groups would negotiate and effectively control the government. This model was intended to diminish traditional ideological conflicts and centre-periphery tensions. As stated previously, until recently Spain has had a strong executive at the expense of the position of Parliament. This was especially the result of the strong position of the socialist party, the PSOE, which held an absolute majority in parliament since 1982. Only since 1996 when the right wing Partido Popular with P.M. Aznar came into government, parliament is starting to become more influential again. Especially since its majority is but a nominal one, obtained with support from the regional Basque and especially the Catalan party.