The casus belli constitutes a classic institute of Public International Law and Constitutional Law, defining the act or circumstance that formally justifies the initiation of a state of war by a sovereign State. Its legal purpose lies in legitimizing the rupture of international peace, grounding the transition from a regime of normalcy to a regime of belligerence under the aegis of state sovereignty.
Concept and Foundation
The casus belli, a Latin expression denoting the cause or legal foundation for war, transcends the mere description of hostilities. It is a concept endowed with a normative nature, acting as the triggering element that confers a veneer of legality to the warlike action of one State against another. Within the scope of general legal theory, doctrine understands it as an international illicit act attributable to a State, which, by violating fundamental rights or the sovereignty of another state entity, authorizes armed self-help.
Historically, the transition from jus ad bellum (right to war) to the prohibition of the use of force, consolidated by the 1945 United Nations Charter, substantially altered the application of the institute. If it was once discretionary, today the casus belli is strictly linked to self-defense (Article 51 of the UN Charter) or authorization by the Security Council.
Historical Evolution and Comparative Law
The evolution of the institute has accompanied the progressive limitation of absolute sovereignty. In Roman Law, fetialism regulated the declaration of war, requiring the pater familias or the Senate to recognize the existence of a just cause. With modernity, contemporary International Law, notably since the Kellogg-Briand Pact (1928), began the proscription of war as an instrument of national policy. In the Brazilian legal system, the constitutional tradition has always sought to align the State with peaceful diplomacy, as prescribed by Article 4, item VI, of the 1988 Federal Constitution (CF/88).
Legal and Constitutional Provision
In the Brazilian legal system, the subject is grounded in the 1988 Federal Constitution, which establishes the rite for the declaration of war. Article 84, item XIX, grants the President of the Republic the exclusive competence to declare war, observing the provisions of Article 137, which requires authorization from the National Congress.
- Art. 84, XIX, CF/88: Competence of the Head of the Executive to declare war.
- Art. 137, CF/88: Requirement of authorization from the National Congress for the declaration of a state of war.
- Art. 4, VI, CF/88: Principle of peaceful settlement of conflicts.
Practical Application and Jurisprudential Understanding
Although there is no direct jurisprudence on the "validation" of a casus belli (given the political nature of the act), the Supreme Federal Court (STF) has expressed, in its decisions on constitutional review and international treaties, the primacy of the UN Charter. Brazilian constitutional jurisprudence, when interpreting sovereignty (Art. 1, I, CF/88), moves away from interpretations that allow for wars of aggression, restricting any foundation of casus belli to the limits of self-defense provided for in the international system.
Related Principles and Doctrinal Divergences
The contemporary debate revolves around the distinction between casus belli and the "responsibility to protect" (R2P). While classical doctrine saw casus belli as a sovereign prerogative, modern doctrine, influenced by ius cogens, argues that massive human rights violations may, under certain conditions, constitute a foundation for international intervention, even if it is not technically classified as war in the classical sense.
Contemporary Relevance and Practical Impacts
The relevance of the institute lies in the containment of arbitrariness. In a global scenario of geopolitical tensions, the invocation of casus belli is subject to rigorous scrutiny by International Humanitarian Law. The practical impact is manifested in the international responsibility of the State, where the absence of a legitimate legal foundation (the casus belli recognized by international norms) can lead to sanctions, economic blockades, and the criminal accountability of state agents before international courts, such as the International Criminal Court (ICC).
Legal and Jurisprudential References
- Constitution of the Federative Republic of Brazil of 1988, arts. 4, 84, and 137.
- United Nations Charter (Decree no. 19.841/1945), art. 51.
- Rome Statute (International Criminal Court), Decree no. 4.388/2002.
- STF, ADI 1.480/DF (Rapporteur Justice Celso de Mello), on the prevalence of human rights and the limitation of state sovereignty.
- Doctrine: Accioly, Hildebrando. Treaty of Public International Law.
