During the reign of James I the Conqueror (1213-1276), the Court of Counts became the General Courts of Catalonia, by gradually increasing the number of members invited and, above all, by consolidating the incorporation of the bourgeois state, represented by leading men from towns and cities. But the decisive step came during the reign of his son, Peter II, the Great (1276-1285), when, at the Barcelona Courts of 1283, via the "Volem, estatuïm"(We want, we decree) Constitution, the system of negotiated rule so characteristic of Catalan medieval and modern constitutional law was established. According to this system, regulations were only valid if they came from the Courts in agreement with the ruler and different feudal land estates, whether on the initiative of the former (constitutions) or the latter (court charters). The dispositions proclaimed by the king in the intervals when the Courts were not called also had to be approved by the Courts (court acts, privileges, pragmatic and other rights). In short, the king renounced his exclusive right to legislative power.

The Catalan Courts were made up of three branches or estates: the military estate, including representatives from the nobility; the ecclesiastical estate, with representatives from the religious hierarchy, and the royal estate, with representatives from the cities and towns within the monarch's dominion. However, large segments of society, such as the peasantry and artisans, were never represented. As a result, and due to the electoral system, although the Courts were a very advanced institution for their time, they were also a reflection of the political concepts and social structure of a feudal society, and cannot be judged by the criteria of contemporary democracies.

The Courts could only be summoned by the king, in any town in Catalonia, and had to be presided over by him personally or by his lieutenant. In spite of successive attempts to hold regular meetings, irregularity was a constant feature. There were monarchs who called them very frequently and others seldom, according to the political expediency of each reign. Once called, the members of the different estates were obliged to attend, barring a just, legitimate impediment. There was an inaugural plenary assembly, where the king set out his proposals, explaining his political agenda and what he hoped to achieve, to which the estates responded. Debate was carried out in separate chambers for each estate, and mediators between them and with the king called tractadors were used to negotiate deals, which were then read and voted on in plenary assembly. In a final plenary, the king solemnly approved the agreements adopted. A session of the Courts could last weeks or months, and even sometimes more than a year, with longer or shorter interruptions.

During the reign of Peter III, the Ceremonious (1336-1387), the institution of the Diputació del General was created (the meeting of the Courts was called the General de Catalunya), with delegated powers to collect and administer the funding the Courts granted to the king. Gradually, the Diputació del General or Generalitat became more autonomous and accumulated executive and governmental powers, and by the 16th and 17th centuries, it was acting as the government for the Principality, defending its constitutional system before the monarchs of the House of Austria, far removed from the country and its interests, and which from the reign of Philip I (II of Castile, 1556-1598), very rarely called the Courts and attempted to govern autocratically.

The first monarch of the Bourbon dynasty, Philip V (1700-1746), respected the rights of the Catalan people by holding the Courts in 1701 and 1702. But in the wake of the succession crisis over the throne of Castile and Catalonia-Aragon, which turned into an international conflict threatening the balance of power in Europe, Catalonia threw in its lot with the archduke Charles of Austria and recognized him as king (Charles III, 1705-1714). Defeat in this War of Spanish Succession (1702-1714), with the consequent fall of Barcelona in 1714, resulted in the victorious Philip V (Felipe V) abolishing all the public laws of Catalonia, along with its representative institutions, through the Decree of Nova Planta or New Proposition (1716), the most important of these institutions being the Courts.