INTERNATIONAL LAW

International Law: subject matter, development and sources

International law is not limited to rules governing external relations between two countries. In its public dimension, it regulates legal relations within international society, involving states, organisations and, depending on the regime, individuals. Its private dimension examines coordination between legal systems in relationships containing foreign elements. Identifying that connection begins the analysis rather than predetermining the competent authority or applicable rule.

Its historical development involves diplomatic practices, trade, conflicts, agreements and different intellectual traditions. Reconstruction of Europe after the Roman world offers one possible historical perspective, but does not establish a scholarly consensus that the entire discipline originated in the Middle Ages. The consolidation of states and forms of cooperation belongs to a broader process that cannot be reduced to linear movement from war to trade.

Treaties play a central role in this development without exhausting the sources. Article 38 of the Statute of the International Court of Justice distinguishes conventions, custom and general principles, while identifying judicial decisions and scholarship as subsidiary means of determining rules. This provision informs understanding of the materials used by the Court; it does not turn every academic opinion or precedent into a universally binding command.

Alliances, peace agreements and commercial instruments illustrate the diversity of international agreements’ purposes. The 1969 Vienna Convention on the Law of Treaties, promulgated in Brazil by Decree No. 7.030/2009 with reservations to Articles 25 and 66, provides a regime for treaties between states. Its use requires identification of the instrument, parties, material and temporal scope, and relevant conditions for producing effects.

Institutions and instruments of cooperation

The League of Nations, United Nations and Organization of American States belong to the history of international organisation and cooperation, but have neither identical institutional identities nor interchangeable powers. Nor should courts and organisations be combined into an undifferentiated category of treaty producers. The source of each entity’s competence must be examined before a particular function is attributed to it.

The International Court of Justice admits states as parties to contentious proceedings under Article 34 of its Statute; jurisdiction depends on the bases in Article 36. The International Criminal Court, governed by the Rome Statute, exercises criminal jurisdiction over persons within that instrument’s limits and according to complementarity with national jurisdictions. It is not a general appellate body for private disputes with foreign connections.

Nor is there a single “Hague Convention” from which chemical weapons, maintenance and trafficking regimes indiscriminately derive. These instruments have their own objects and histories. The convention prohibiting development, production, stockpiling and use of chemical weapons and requiring their destruction was promulgated by Decree No. 2.977/1999. The instruments on international recovery of maintenance and the law applicable to maintenance obligations, concluded at The Hague in 2007, were promulgated by Decree No. 9.176/2017. The presence of two instruments in that decree requires distinction between cooperation for recovery and determination of applicable law.

The protocol to prevent, suppress and punish trafficking in persons, especially women and children, supplements the United Nations Convention against Transnational Organized Crime and was promulgated by Decree No. 5.017/2004. Identifying these texts does not establish their application to every situation: subject matter, scope and relations between countries require separate verification. Thematic proximity permits neither conflation of conventions nor attribution of their origins to the same forum.

Public International Law

Public international law encompasses rules concerning subjects, powers, responsibility, cooperation and dispute settlement within international society. Its subject matter is not defined solely by collective interests or an institution’s public character. Individuals’ rights and duties may also form part of specific regimes, while state participation in an economic relationship does not, alone, resolve every question of legal classification.

Connections with constitutional, administrative, tax and criminal law matter, but create no uniform legislation above the constitution for every country. Fundamental rights, international organisations, cross-border taxation and suppression of crime have their own sources and methods. Academic classification helps organise the subject; it does not remove the need to identify the binding rule or competent procedure for applying it.

Sovereignty and peoples’ self-determination must be reconciled with international obligations rather than turned into justifications for arbitrary interference. The United Nations Charter regulates sovereign equality, peaceful settlement and prohibition of the threat or use of force. Article 2, §§ 4 and 7, Chapter VII and Article 51 have distinct functions and requirements. Political disagreement or a generic invocation of human rights does not provide indiscriminate authorisation for military intervention.

In Brazil, Article 4 of the Constitution sets out international relations principles, including national independence, primacy of human rights, self-determination, non-intervention and peaceful settlement of disputes. Legal assessment of a concrete measure requires examining those foundations alongside institutional competence and the international rule invoked, rather than presuming lawfulness or illegality from the participants’ political affinities.

Private International Law and its relationship with the public dimension

Private international law addresses jurisdiction, applicable law, cooperation and effectiveness of foreign acts in internationally connected private relationships. Trade, corporate organisation, real property, family and succession provide examples. Substantive rules within each field remain relevant: selecting the law governing a contract differs from deciding its content, and identifying the forum does not necessarily entail applying that country’s law.

The distinction from public international law does not eliminate points of contact. Treaties may establish mechanisms for recovery, circulation of decisions and procedural communications benefiting private parties. Domestic rules also coordinate legal systems, as with the Introductory Law to Brazilian Legal Norms. Transnational activity does not invariably depend on a specific treaty previously concluded between the states concerned.

The unity or autonomy of these disciplines is a matter of doctrinal construction. In legal work, bringing them together must preserve differences in subjects, sources and effects. The fact that a private transaction generates taxes funding public activities does not make the commercial contract, tax obligation and state’s international commitment identical. Each relationship requires its own basis and classification, even within the same economic context.

Likewise, an individual’s ability to acquire goods from another country is not determined solely by the political orientation of the respective governments. Rules actually applying to the transaction must be examined, including possible trade restrictions, customs requirements or specific measures. Opposition between “public interest” and “private interest” neither replaces that examination nor justifies presumed prohibition or unrestricted freedom.

The judiciary and the internationalisation of law

A Brazilian judge may apply foreign law where the relevant rule so provides. The LINDB contains provisions on personal and family matters, property, obligations and succession, particularly in Articles 7 to 10. A connection to another country does not itself exclude Brazilian jurisdiction, just as a national court’s competence does not necessarily make Brazilian substantive law applicable to the relationship.

Article 7 of the LINDB uses domicile for certain personal matters; this does not turn every procedural-capacity issue into automatic application of domiciliary law. The problem must be classified before selecting a connecting rule. Under Article 14, where the judge does not know the foreign law, proof of its text and current force may be required. Article 17 limits effectiveness of foreign laws, acts, judgments and declarations by reference to national sovereignty, public policy and good morals.

Determining international jurisdiction is a distinct stage. Articles 21 to 23 of the Code of Civil Procedure establish Brazilian jurisdiction and matters reserved to national authorities. An event occurring or an act performed in Brazil is one statutory criterion rather than a basis for asserting that every territorially connected situation belongs exclusively to Brazilian courts without exception. Other provisions and applicable treaties must also be considered.

Foreign decisions may produce effects in Brazil through the relevant recognition regime. Article 105(I)(i) of the Constitution assigns recognition of foreign judgments and exequatur for letters rogatory to the Superior Tribunal de Justiça. Articles 960 to 965 of the CPC regulate the subject, imposing requirements and limits that prevent both blanket refusal of effectiveness and automatic acceptance of every ruling.

Article 961, § 5, of the CPC provides that a foreign judgment granting a consensual divorce produces effects without recognition by the STJ. This does not remove the need to examine the decision’s actual content and requirements applicable to the intended effects. Applications involving assets, maintenance, custody or other parts of the decision require their own classification; the document’s label does not, alone, resolve its treatment.

International cooperation follows Articles 26 to 41 of the CPC and the relevant instrument. Direct assistance, letters rogatory and recognition are not mandatory stages of a single sequence: their objects and requirements differ. The Central Authority receives and transmits requests within its functions; judicial decisions belong to the competent court. Documents, language, the opportunity to be heard and the act’s purpose must be organised according to the selected route.

The relationship between international and national law

No uniform answer on precedence applies to every international rule and domestic subject. The basis of international commitment, the process by which it is formed, its domestic effects and its position within the constitutional system must be distinguished. Custom, treaties and institutional acts do not necessarily follow the same formation or evidentiary path.

For treaties, Articles 49(I) and 84(VIII) of the Constitution allocate powers between Congress and the President of the Republic. Parliamentary approval must not be confused with every stage of concluding and implementing a commitment. The instrument’s text, promulgating act and international status provide different information; signature, ratification and entry into force are not equivalent expressions.

Article 5, § 2, permits rights and guarantees arising from treaties to which Brazil is party. Section 3 establishes equivalence to constitutional amendments for human rights treaties and conventions approved in each House of Congress, in two rounds, by three fifths of its members. This specific provision neither establishes that every treaty ranks above the Constitution nor makes every international rule enter domestic law automatically in the same way.

Professional application therefore requires identification of the source and demonstration of why it binds the subjects concerned. The obligation’s scope, relevant domestic rule and mechanism for resolving any conflict must then be examined. Abstract criteria about a proposition’s generality or objectivity may contribute to theory, but do not replace proof of the rule and its application requirements.

Professional education and continuing development

Intensifying economic, family and technological relationships between countries broadens the variety of problems submitted for legal analysis. This observation is neither a demand forecast nor a career guarantee or authority to practise in every jurisdiction. The work requires a defined engagement, verified sources, understanding of procedure and coordination with professionals where execution depends on local admission or knowledge.

Academic development should accompany experience and continuing review of sources. Reading a treaty must include its scope and status; case-law research must distinguish the holding actually decided from an incidental reference; practical advice must separate mandatory requirements from strategic choices. A consistent method turns international law’s breadth into responses appropriate to the case, without reducing its internal differences to a generic definition.

Related reading

Education and admission limits are examined in International Legal Practice: How to Specialise?. For cooperation routes and execution of foreign acts, consult Letters Rogatory and the Execution of Foreign Acts in Brazil. Career organisation is developed in A Career in International Law — International Lawyer.