Introduction to Public International Law

Note on Introduction to Public International Law by Legum

Introduction to Public International Law:

Public international law is one of the two main sub-divisions of international law and refers to the set of rules governing the activities of states and their relationship with other states, international organizations, and other subjects of international law.

Contemporary public international law is the outcome of centuries of inter-state relations and agreements. Earlier conceptions of public international law were that it regulates the activities between states. However, public international law today goes beyond states to include Non-Governmental Organizations, Multinational Corporations, International Organizations, and sometimes individuals. Further, contemporary public international law seeks to regulate areas such as human rights, environmental pollution and preservation, and refugees among others.

Mostly, international law and public international law are used synonymously. Shaw (2019, para 1) for instance, asserts that international law is also known as public international law and refers to “the body of legal rules, norms, and standards that apply between sovereign states and other entities that are legally recognized as international actors.” However, international law can be divided into public international law and private international law.

Differences Between Public International Law and Private International Law:

1. In terms of Definition: private international law, also known as conflict of laws, is the set of rules and principles that apply when a legal dispute involves individuals of different nationalities. For example, a divorce case involving an American and a Ghanaian is an instance of private international law because it raises questions of which country’s laws would apply among others. The contract law case of Entores v Miles Far East Corporation is an example of private international law, as it involves a legal dispute between a London-based company, Entores, and Miles Far East Corporation, a company based in Amsterdam. Public international law, on the other hand, simply regulate the activities of states, and international organizations among others.

2. In terms of Subjects: Public international law primarily deals with nation states and their conduct and interactions, whilst private international law deals with individuals of different states.

3. Sources of law: In public international law, common sources of law are treaties, customary laws, and judicial decisions by international bodies such as the International Court of Justice, among others. See Article 38 of the Statute of the International Court of Justice for sources of (public) international law. For private international law, the sources of law are essentially the laws of the state concerned. For instance, the court in Entores v Miles Far East Corporation held that the contract was formed in London, and the laws of the United Kingdom were used to adjudicate the dispute.

4. Consequences of Violation: When there is a breach of public international law, other states usually mete out punishments to the breaching state. In the recent dispute involving Russia and Ukraine, considered by most states to be a violation of Article 2(4) of the United Nations Charter, various states have sanctioned Russia for the violation. In private international law, however, the laws of the State used to adjudicate the dispute stipulates the consequences of breach.

Differences between Public International Law and Municipal Law or National Law:

Beyond the distinction between public international law and private international law, public international law is also different from municipal law, also known as the domestic or national laws of states. The difference is in three key areas:

1. Law-making: Municipal laws, thus the laws of a state, are made by a designated body of persons usually known as legislators. In the United Kingdom, for instance, this is the House of laws and the House of Commons. In Ghana, this is Parliament. In international law, however, no such body exists. “Laws” in international law are at best created by states through treaties among others.

2. Law enforcement: In municipal law, laws are usually enforced by the executive branch of government. The police, for instance, ensure that the laws are not breached and that offenders are arrested. In international law, however, no such system exists, and violations of international law by a state are instead “punished” by other states through sanctions among others.

3. Application: In international law, the rules of treaties are only binding on states that consent to be bound by being a signatory to the treaty. The United States, for instance, is not a party to the Rome Statute, consequently preventing the International Criminal Court from prosecuting an American citizen for crimes committed on American soil. With domestic law, however, citizens do not have to consent to be bound by the laws of the country, and any violation by any citizen would be punished.

4. System of courts: Municipal laws usually provide for several courts with a clearly defined hierarchy and jurisdiction. In most countries, there is a supreme court, a court of appeal, a High Court, and other divisional courts. In international law, however, no such system of courts exists.

The Big Debate: Is International Law, Law?

Some characteristics of international law, such as the non-existence of an international police force to prevent violations of international law, and no central legislature to create laws, among others, have led many to question whether international law is law. The arguments for and against the motion that international law is not law shall now be considered.

1. Some claim that international law is not law because law ought to have an enforcement mechanism, and international law does not have such a mechanism. Municipal laws are considered laws because there exists a state police system empowered to punish violators of the law, and ensure compliance with the law. Consequently, the non-existence of such a system in international law has led to the conclusion that the rules in international law cannot be considered law. Several international law scholars have countered this argument. D'Amato (1985) for instance contends that international law is enforced by a “reciprocal-entitlement violation”. D'Amato (1985) argued that similar to how state governments deny citizens their entitlement (such as freedom of movement) when they commit a crime, other states deny the state in breach of international law of its entitlements, and may institute counter-measures against the state in breach, among others.

2. An extension of the lack of enforcement argument is that international law is not law because there exists no system of courts with the authority to adjudicate international disputes using international law, unless with the consent of the disputing states. Whilst this argument is true, especially due to consent being a fundamental element in international law, the fact that states voluntarily submit their disputes to international legal bodies like the International Court of Justice, herein the ICJ, shows that states aim to, and do resolve their disputes through a court system or an international legal body. In the case of Chad v Libya, Chad and Libya submitted their territorial dispute over the Aouzou Strip to the ICJ for a resolution, and the ICJ resolved the dispute in favour of Chad using the 1955 Treaty of Friendship and Good Neighbourliness. Similarly, in the case of New Zealand v France (the Rainbow warrior case), an international arbitration tribunal found France to be in breach of its agreement with New Zealand.

3. Some also contend that international law is not law because of the possibility of powerful states violating international law without any punishment. However, domestic laws equally suffer from this challenge as powerful individuals may violate state laws without any punishment.

4. Finally, some argue international law is not law because of the absence of a law-making body, commonly known as the legislature in domestic contexts. However, it can be argued that a definite body of lawmakers is only one way of making laws, and there could be other ways. For instance, military governments may make laws through decrees, and such laws are considered law. Similarly, states could, through treaties and other systems, make laws to regulate international activities.

In conclusion, this note defined public international law and distinguished it from municipal law and private international law. It also examined arguments for and against the idea that international law is not law.


D'Amato, A. (2010). Is international law really 'law'? Faculty Working Papers.

Shaw, M. (2019, November 13). International Law. Retrieved from Britannica: