A system composed solely of legal rules and principles binding upon civilized nations only in their mutual relations.

Austin’s opposition to international law stems from his definition of law. According to Austin, law “properly so called” is the command of the sovereign, backed by a superior political authority. In other words, law is the edict issued from a determinate sovereign legislative authority that must be backed by the authority of the State. ... If the concerned rules were not issued by the sovereign authority, then they cannot be legal rules.

Critics of international law argue that it differs remarkably from municipal law in many respects such as the absence of an elected legislature to frame laws, the absence of courts with compulsory jurisdiction over all disputes or the absence of an independent third-party dispute- settlement mechanism, and the lack of effective sanctions to punish those subjects (states) who break the rules.

States adopt certain rules of international law only because they voluntarily restrict their sovereignty. The sovereignty is absolute unless a State agrees to its limitation. This is known as auto limitation theory.

Codification means “the more precise formulation and systematization of rules of international law in fields where there already has been extensive State practice, precedent, and doctrine.”

monism and dualism

The theory of monism regards that both international law and municipal law have a common underlying legal basis, which derives its origin from the law of nature and binds both States and individuals

The theory of dualism grew out of the nineteenth-century positivist philosophy that emphasizes the will of the State as the sole criterion for establishing international rules. According to the dualist theory, international law and municipal law operate on different levels. While international law regulates mainly the relations and obligations between sovereign States, municipal law operates and regulates the relations and obligations of individuals within a State.

Since dualists attach significance to the sovereignty of the State will, they give primacy to municipal law over international law. Because the State is independent, it should enjoy complete liberty and exercise full sovereignty. On the other hand, monists are divided on this issue. Some monists give primacy to international law while others to municipal law.

Traditional definition of international law emphasizes legal rules and principles binding upon civilized nations only in their mutual relations while the modern definition emphasizes the relations not only among states but also between states and other subjects of international law.

Critics always draw a parallel with municipal (State) law and are wary of the absence of a legislative body, the hierarchy of courts, and enforcement machinery under international law. They argue there is no machinery at the international level that is similar to a State that would make, implement, and enforce law. The breaches of international law that led to wars or armed conflicts, non-observance of treaty obligations, and other blatant violations of international law have been quoted as examples of total absence of an international legal system. Critics have also used the absence of effective sanctions as another reason for challenging its legal character.

Countermeasures are unilateral measures adopted by a State (the ‘injured State’) in response to the breach of its rights by the wrongful act of another State (the ‘wrongdoing’ or ‘target’ State) that affect the rights of the target State and are aimed at inducing it to provide cessation or reparations to the injured State (Oxford Public International Law).

The Kellogg-Briand Pact: A multilateral agreement condemning war. It grew out of a proposal by the French Premier, Aristide Briand, to the US government for a treaty outlawing war between the two countries. The US Secretary of State, Frank B. Kellogg, proposed a multilateral treaty of the same character. In August 1928, 15 nations signed an agreement committing themselves to peace; the USA ratified it in 1929, followed by a further 46 nations. The failure of the Pact to provide measures of enforcement nullified its contribution to international order.

Ubi Societas Ibi Jus is a legal maxim which means ‘where there is society, there is law’. This maxim revolves around the concept that law and society are indivisible. The maxim states that law is indispensable to every society. Maintenance of peace and harmony of a society will happen in its entirety only if there is a law for the society.

They believed in the primacy of customary rules and treaty rules. According to these jurists, the rules of international law and municipal law are equally binding, since both are created by the will of the State that is the source of the validity of law. In other words, it isthe will of the State that commands obedience both in municipal law and international law.

Oliver J. Lissitzyn suggests, there are three reasons for obeying the law: self-interest, sense of moral obligation, and habit. Of these three, self- interest is probably the most basic reason for the observance of international law.

The true basis of international law lies neither exclusively in natural law nor solely in the consent of States, but in variety of factors that impel States to obey the law. Most rules of international law are based on similar and complementary interests of nations. Self-interest appears to be the basic reason for compliance, and voluntary compliance generally does not need any specific enforcement.

Development of modern international law can be studied under two distinct headings: development during the classical period and development since World War I.