Is the application of treaties and conventions under International Law subject to their domestication by states?

By: Adekunle Adebajo, University of Ibadan



Because of their written and easily verifiable nature, treaties are one the most important sources of international law, rules, principles and guidelines. They are more or less like terms and conditions in a contractual agreement, with every term subject to scrutiny and confirmation at every point in time. This crucial quality nonetheless, unlike typical contracts and municipal legislations, the enforcement of treaties is not often straightforward. Several factors are involved in the determination of the applicability of every treaty within each state.

There are two major approaches when it comes to the question of the status of treaties in domestic legal systems. While some states follow the dualist approach to the question, others follow the monist approach.



Under the dualist approach, treaties are part of a separate legal system from that of the domestic law. They do not form part of domestic law directly. Consequently, a treaty is not automatically operative within a state which consents to be bound by a treaty or convention unless and until an appropriate national legislation has been enacted to give it municipal force.

According to the dualists, the rules of the systems of international law and municipal law exist separately and cannot purport to have an effect on, or overrule, the other; a recognition of the fundamentally different nature of inter-state and intra-state relations and the different legal regimes used in municipal law and international law. Being separate systems, international law does not as such form part of the municipal law of a state.

When in particular instances rules of international law may be applicable within a state, they do so by virtue of their adoption by the internal law of the state, and apply as part of that internal law and not as international law. Therefore the question of the supremacy of one system of law over the other is avoided since they share no common field of application. Each is supreme in its own sphere.



On the other hand is the monist approach where the state’s legal system is traditionally deemed to include treaties which that state has consented to. In other words, treaties become self-executing and automatically binding domestically. The treaty becomes a source of law, and there is no need for reliance upon the legislative body or any other state agent to ratify the treaty for it to become locally applicable.

The monists accept a unitary view of law as a whole based either on formalistic logical grounds as espoused by Kelsen[1], or strong ethical concerns as argued by Lauterpacht.[2] Thus, the monists submit that the various national systems derive from the international legal system. Since international law can therefore be seen as essentially part of the same legal order as municipal law, and as superior to it, it can be regarded as incorporated in municipal law. Consequently, there would be no difficulty in its application as international law within states.

The general rule is that a state which has broken a rule of international law cannot justify itself by referring to its municipal law; otherwise international law would be evaded by passing appropriate domestic legislation.[3] Article 27 of the Vienna Convention on the Law of Treaties, 1969, is very clear about this, while article 46(1) provides that a state may not invoke the fact that its consent to be bound by a treaty has been expressed in violation of a provision of its internal law regarding competence to conclude treaties as invalidating its consent. Under the principle of pacta sunt servanda, a state is under the duty to honour its international obligations even if it means changing its municipal law. This view has been applied in various international cases.

The British in the Alabama Claims Arbitration,[4] sought to rely on lack of domestic legislation to avoid liability. Their defence was defeated on the ground that the British government could not justify itself for a failure in due diligence on the plea of insufficiency of the legal means of action it possessed. There is a general duty to bring municipal law into conformity with obligations under international law. As decided in the Exchange of Greek and Turkish Populations Case[5] a state which has contracted valid international obligations is bound to make in its legislation such modifications as may be necessary to ensure the fulfilment of the obligations undertaken. If it does not do so, a state cannot rely on her own legislation to limit the scope of her international obligations.[6] It is a generally accepted principle of international law that in relations between states who are contracting parties to a treaty, the provisions of municipal law cannot prevail over those of the treaty;[7] even if that municipal law is the state’s own Constitution.[8]

Likewise, a state once it has ratified a treaty, cannot successfully amend its domestic legislation with a view to evading obligations incumbent upon it under international law. In such a situation, international law prevails over municipal law. As stated in the United Nations Headquarters opinion, on the international legal plane, national law cannot derogate from international law.[9] Thus, a state that is uncertain about the compatibility of its policy on a particular issue would desist from ratifying a treaty that would oblige it to amend legislation that it is not ready to amend, especially so in view of the numerous international law decisions in this area.



Examples of dualist countries are Kenya, Uganda, Nigeria and the United Kingdom. In Kenya, the authority to sign treaties vests, by practice, with the Minister of Foreign Affairs. This is a grey area in which there is no express law, and this ministerial practice has now attained the force of law. As regards the ratification process, there is no specific ratification act as such but the process is regulated through the administrative process of government circulars and “regulations”. If an international convention concerns a specific Ministry, that Ministry prepares a cabinet paper relating to that convention for cabinet approval. Thereafter, the instrument of ratification and accession is prepared, signed and deposited by the Ministry of Foreign Affairs.

In the case of East African Republic versus Republic[10], it was held that the provisions of a treaty entered into by the Government of Kenya do not become part of the municipal law of Kenya save in so far as they are made such by the law of Kenya. Thus the dualist position prevails in Kenya.

Similarly, in Uganda, while the President or a person authorised by him has the powers to make international agreements or other arrangements between Uganda and any other country or body, The Ratification of Treaties Act, 1998, provides that Cabinet is responsible for the ratification of all treaties except treaties that relate to armistice, neutrality or peace; or treaties in respect of which the Attorney-General has certified in writing that its implementation would require an amendment of the Constitution.[11] Such treaties can only be ratified by Parliament by resolution.

In the same vein, the 1999 Nigerian Constitution under section 12(1) provides:

No treaty between the Federation and any other country shall have the force of law to the extent to which any such treaty has been enacted into law by the National Assembly.

On the other hand are countries such as Austria, Italy, France and Germany. There they operate a one-tier legal system with the primacy of international law over national law. The Dutch Constitution also provides that international treaties to which the State is party shall prevail over national law unless otherwise provided.

The United States has a mixed system of monism and dualism. This is because international law applies directly in US courts in some instances but not in others. Article VI of the United States Constitution provides that treaties are part of the Supreme Law of the Land. However, the Supreme Court has stated, such as in the case of Medellin v. Texas[12], that some treaties are not “self-executing” and must be implemented by statute before their provisions may be given effect by national and sub-national courts.

Thus in answering the question, there appears to be no hard and fast rule. While the legal tradition of some countries puts them under the umbrella of monism, other countries are generally considered to have a dualist status. In dualist countries such as Kenya, Uganda and Nigeria, international treaties and conventions are subject to ratification by domestic authorities before they can be applied locally. On the other side of the divide are countries such as the United States, Italy, Netherlands, France and Germany where they operate a mostly monist system and international laws are given a free reign of application in so far as the state is a party to the treaty or convention.



[1] General Theory of Law and State, 1945.

[2] International Law and Human Rights, London, 1950.

[3] SHAW N. Malcolm, International Law, 4th Ed., Cambridge University Press, 1998, p.102.

[4] (1872)1 Int. Arb. 495.

[5] 1925 P.C.I.J. Reports Series B No.10.

[6] The Free Zones Case, 1932 P.C.I.J. series A/B No. 46.

[7] The Greco-Bulgarian Communities Case (1930) P.C.I.J. series B. No.17.

[8] The Polish Nationals in Danzing case (1931) P.C.I.J. series A/B, No. 44.

[9] Judge Schwebel in 1988 I.C.J. Reports, 11.

[10] (1970) E.A 457

[11] Section 3, Ratification of Treaties Act, 1998.

[12] 552 U.S. 491 (2008).

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