What is International Law?
International law is the branch of law that regulates relations between states, international organizations, and, in some cases, individuals. Its objective is to establish rules for cooperation and coexistence among nations, guaranteeing legal certainty and stability in the global order.
Unlike domestic law, which is imposed by a sovereign state on its citizens, international law depends on the cooperation and consent of the parties involved.
Public International Law and Private International Law
Public International Law deals with the rules governing relations between States and international organizations. It includes topics such as treaties, war and peace, sovereignty, human rights, and conflict resolution. It is applied, for example, in the decisions of the United Nations (UN) and in the judgments of the International Court of Justice (ICJ).
Private International Law, on the other hand , regulates legal relationships between individuals or companies from different countries. It, in turn, defines which national legislation should be applied in transnational disputes, such as international commercial contracts, marriages between citizens of different countries, and the extradition of criminals.
Sources of International Law
The Statute of the International Court of Justice , in Article 38, defines the main sources of International Law:
- International Treaties – Agreements formally concluded between States or international organizations, such as the Vienna Convention on the Law of Treaties.
- International Customs – Practices repeated by States that are accepted as legally binding, such as diplomatic immunity.
- General Principles of Law – Universal norms accepted by various legal systems, such as good faith and fairness.
- Judicial Decisions and Doctrine – Judgments from international tribunals and the work of specialized jurists are used to interpret and apply international law.
1. Foundations of International Law
International law is based on several fundamental principles that guide the creation, interpretation, and application of its norms. Among the main ones are the consent of states, international customs, treaties, general principles of law, as well as jurisprudence and doctrine.
1.1. The consent of States
Sovereignty is a fundamental principle in International Law, granting States supreme authority over their territory and independence in foreign relations. In this context, state consent is essential for the formation of binding international norms.
States express their consent through the signing and ratification of treaties, committing themselves to fulfill the obligations established therein, according to the principle of pacta sunt servanda , which ensures the observance of the agreements signed.
1.2. International Custom
International custom constitutes a primary source of international law, deriving from a general practice of states accepted as legally binding.
For a practice to be recognized as custom, it must be consistent and widely adopted by States, accompanied by opinio juris , that is, the conviction that such practice is required by a legal norm.
Examples include diplomatic immunity and the principle of non-intervention in the internal affairs of other states.
1.3. International treaties
Treaties are formal agreements between states or international organizations, intended to produce legal effects. They play a fundamental role in the codification and development of international law.
The process of forming a treaty generally involves negotiation, signing, ratification, and entry into force. Signature indicates initial agreement with the text, while ratification, according to each State's internal procedures, confirms consent to be legally bound by the treaty.
1.4. The general principles of law
Recognized by the Statute of the International Court of Justice as sources of international law, general principles of law are fundamental norms common to the major legal systems of the world.
Among them, the following stand out: good faith, which requires the loyal observance of obligations undertaken; equity, which seeks justice and impartiality in the application of law; and reciprocity, which ensures mutual benefits and obligations between States.
2. Fundamental Principles of International Law
International law is governed by fundamental principles that guarantee order and cooperation among states. These principles establish the basis for peaceful coexistence, the protection of human rights, and global security, and are widely recognized in treaties, conventions, and international practice.
2.1. Sovereignty and equality of States
Sovereignty is one of the pillars of International Law, guaranteeing that each State has supreme authority within its territory and independence in its external decisions. This principle ensures that States are not subject to any other superior authority, except when they voluntarily accept limitations, such as in treaties and international organizations.
Another fundamental aspect is sovereign equality, which establishes that all States, regardless of their size, economic power, or political influence, have equal rights and duties before the international community.
Equality does not mean uniformity, but rather mutual respect for state prerogatives. Furthermore, the principle of non-intervention reinforces that no state can interfere in the internal affairs of another, except in exceptional cases authorized by international law.
2.2. Autonomy of peoples
The principle of self-determination ensures that peoples have the right to freely decide their political, economic, social, and cultural destiny. This principle underpins the creation of new states and the struggle against colonial, discriminatory, or oppressive regimes.
Historically, self-determination was a decisive factor in the decolonization of Africa and Asia, resulting in the independence of several nations. Currently, this principle continues to be debated in contexts such as the independence of Palestine and the right to self-determination of regions like Catalonia and Kashmir.
However, its application must be balanced with the territorial integrity of states to avoid destabilizing conflicts and fragmentation.
2.3. Prohibition of the use of force
The prohibition of the use of force between States is an essential principle for maintaining international peace and security. The Charter of the United Nations , in its Article 2, establishes that members must refrain from the threat or use of force against the territorial integrity or political independence of any State.
However, there are exceptions to this prohibition. The right to self-defense , enshrined in Article 51 of the UN Charter, allows States to use force if they suffer an armed attack. Furthermore, military operations may be authorized by the UN Security Council , as has occurred in humanitarian interventions or peacekeeping missions to restore order in unstable regions.
2.4. Peaceful resolution of conflicts
International law prioritizes the peaceful resolution of disputes between states, encouraging the use of diplomacy and non-violent means to resolve conflicts. International organizations, such as the UN and the International Court of Justice (ICJ) , play an essential role in preventing disputes and enforcing legally binding decisions.
Dispute resolution methods include negotiation , in which states engage in direct dialogue to resolve disputes; mediation , in which a neutral third party facilitates an agreement; arbitration , which involves the creation of a temporary tribunal to decide the case; and judicial settlement , in which international tribunals establish resolutions based on international law.
2.5. Protection of Human Rights and Human Dignity
The recognition of human rights protection in international law represents a significant step forward in limiting state sovereignty in favor of human dignity. Instruments such as the Universal Declaration of Human Rights (UDHR) and treaties such as the International Covenant on Civil and Political Rights have established global standards to guarantee fundamental rights such as freedom, equality, and security.
International tribunals, such as the International Criminal Court (ICC) and the European Court of Human Rights (ECHR) , reinforce the accountability of individuals and states for serious violations, including genocide, war crimes, and torture.
Thus, the protection of human rights has become an essential principle of International Law, ensuring that human dignity prevails over political or economic interests.
The closing thought
International law is fundamental to regulating relations between states, organizations, and individuals, guaranteeing global cooperation, sovereignty, and the protection of human rights. Its effectiveness depends on the commitment of states and the actions of international tribunals in resolving disputes.
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References
ACCIOLY, Hildebrando; SILVA, GE do Nascimento e; CASELLA, Paulo Borba. Manual of Public International Law. 25th ed. São Paulo: Saraiva Jur, 2021. E-book. (1 online resource). ISBN 9786555594836. Available at: https://integrada.minhabiblioteca.com.br/books/9786555594836.
TEIXEIRA, Carla Noura. Manual of public and private international law : includes human rights. 6th ed. São Paulo: Saraiva Jur, 2023. E-book. (1 online resource). ISBN 9786553624511. Available at: https://integrada.minhabiblioteca.com.br/books/9786553624511.
