The Court is composed of 12 judges (2 linguistic groups of which 6 Dutch and 6 French speakers, one of them must have an adequate knowledge of German) appointed for their lifetime by the King (in practice, the federal government) within a list of candidates provided by the federal parliament.

In Belgium, the appointment of judges follows a complex process involving several institutions, and it is intertwined with the country's linguistic diversity. Here is an outline of the procedure:

The High Council of Justice (HCJ) in Belgium plays an essential role in selecting judges. This body is divided equally between Dutch-speaking and French-speaking members, maintaining linguistic balance. The Council publicizes vacancies for judicial positions and accepts applications. It screens the applicants through various criteria, which may include experience, skills, qualifications, and knowledge of the law.

Once shortlisted, the candidates are interviewed by a panel. The HCJ then provides a list of the most suitable candidates to the Minister of Justice. The Minister of Justice presents the list to the King (a largely ceremonial role), who officially appoints the judges.

Regarding the linguistic balance, it's crucial to understand that Belgium has complex linguistic arrangements to ensure representation of all communities in governance. For example, the Belgian federal parliament consists of two chambers: the Chamber of Representatives and the Senate.

The Chamber of Representatives has 150 members elected for a five-year term. 88 seats are for the Flemish-speaking electorate, 62 seats are for the French-speaking electorate, and there's a seat for the German-speaking electorate. Members of both linguistic groups have a say in most matters, including the selection of judges.

In the Senate, it's more complicated. There are 60 senators, of which 50 are appointed by the communities and regions and 10 are co-opted senators. Of these 50, 29 are elected from the Flemish Community, 20 from the French Community, and 1 from the German-speaking Community.

There's an unofficial agreement in the Belgian federal parliament that the two main linguistic groups (Flemish and French) generally will not block the judicial candidates from the other group. This principle is rooted in the concept of 'consociational democracy,' practiced in Belgium, where power is shared among different linguistic and community groups to ensure smooth functioning of the State. However, this is not a codified or formalized agreement, and exceptions can occur.

The rigid application of the territorial principle governs the judicial system and its linguistic organization in Belgium, with the exception of bilingual areas. The question is less about "why is it like this?" and more about "how could it be otherwise?"

The entire institutional system, including the judiciary, is divided to ensure a balance that guarantees cohabitation and peaceful coexistence between two opposing communities. The principle of territoriality and a preference for monolingual regimens are applied whenever possible to maintain this balance. In other cases, equal participation by the Flemish and French-speaking components is ensured.

This balance is particularly evident in the Constitutional Court. As one view posits, "la règle de la parité ne peut être assimilée à une disposition sur l’usage des langues au sein de l’institution de justice. Elle doit être comprise dans une perspective plus institutionnelle. Elle est révélatrice de la structure dualiste de la société politique..." In essence, this perspective views the equal representation as indicative of the dualistic structure of the political society.

The Court's composition from a linguistic point of view, the selection of its members (chosen from linguistically determined lists, drawn up by the Lower House and the Senate), and its internal organization (with two presidents, one from each of the two linguistic communities, and assistance of referendaries also divided into linguistic groups) fulfil the need to position the Court as a guarantor of the institutional balance.

The Constitutional Court in Belgium is widely believed to contribute to the orderly and peaceful functioning of the federal enterprise. It represents the unity in diversity upon which Belgium is built, better than any other body. The Constitutional Court oversees the respect for so-called federal loyalty - an essential ingredient of the cohesion of the Belgian State, which serves as a reminder to the various political actors that beyond formal respect of competencies, they must ensure the purpose of the political project.

This unwritten principle is often connected with another founding pillar of the system - that of living together, united with the concept of community peace. With this perspective, an indissoluble link is formed between the Constitutional Court, linguistic separation, and federal loyalty. This amplifies the Court's role as the keeper of the federal system and guarantor of the reliability of the system with respect to the claims of the people.