The Legality of Unilateral Economic Sanctions in International Law
By Muhammadjawad Oloruntoyin
Introduction
Economic sanctions have become one of the most frequently employed instruments in contemporary international relations. They are generally understood as restrictive economic measures adopted to induce a State to comply with international obligations or accepted norms of conduct. Under international law, the United Nations Security Council (hereafter referred to as UNSC) possesses primary responsibility for the maintenance of international peace and security and is expressly empowered under Chapter VII of the United Nations Charter to impose collective sanctions. Article 41 of the Charter authorises the UNSC to decide on measures not involving the use of armed force, including economic and diplomatic sanctions, which are binding on all Member States.
However, beyond the framework of the UNSC, States, acting individually or collectively, have increasingly resorted to economic sanctions without express Security Council authorisation. This development raises a fundamental legal question about whether unilateral economic sanctions are lawful under international law. This essay examines that question by analysing unilateral sanctions from two perspectives: sanctions imposed by a single State and sanctions imposed by a group of States outside the UNSC framework. It further evaluates arguments for and against their legality and proposes a way forward for greater legal certainty and fairness in the international system.
Sanctions Imposed by a Single State
The imposition of economic sanctions by one State against another remains one of the most controversial practices in international law. Such measures are often adopted by economically or politically powerful States against weaker States, as seen in sanctions imposed by the United States against countries such as Cuba, Iran, and Nicaragua. The legality of these sanctions largely depends on their legal basis and the circumstances under which they are imposed.
Where economic sanctions arise from a bilateral treaty, their legality is relatively uncontroversial. In such cases, the parties are bound by the principle of pacta sunt servanda, and sanctions imposed pursuant to agreed treaty provisions are lawful as a matter of consent. The legal difficulty arises where sanctions are imposed in the absence of any treaty relationship or UNSC authorisation.
In this context, international law places significant emphasis on the principles of sovereign equality of states, non-intervention, and self-determination, as enshrined in Articles 2(1) and 2(7) of the UN Charter. In Military and Paramilitary Activities in and against Nicaragua (Nicaragua v United States of America), the International Court of Justice (ICJ) affirmed that coercive measures interfering with a State’s freedom to determine its political, economic, and social system may violate the principle of non–intervention. Although the case primarily concerned the use of force, it underscores the broader prohibition against coercive interference in the internal affairs of States.
Further limitations on unilateral economic sanctions can be inferred from specialised treaty regimes. For instance, Article VIII(2)(a) of the Articles of Agreement of the International Monetary Fund (IMF) restricts member States from imposing exchange restrictions on other members without IMF approval. While this provision does not amount to a general prohibition of sanctions, it illustrates how international economic law constrains unilateral financial measures.
Nevertheless, international law does not categorically prohibit all unilateral economic sanctions. States retain sovereignty over their economic relations and may adopt retorsion, that is, unfriendly but lawful acts such as the withdrawal of aid or trade preferences. Additionally, under customary international law as reflected in the International Law Commission’s Articles on State Responsibility, a State may adopt countermeasures in response to a prior internationally wrongful act, provided such measures are proportionate, temporary, and aimed at inducing compliance. The legality of unilateral sanctions by a single State therefore depends on whether they satisfy these strict conditions.
Sanctions Imposed by a Group of States Outside the UNSC
A further dimension of the debate concerns economic sanctions imposed by a group of States, often acting through regional or sub-regional organisations such as the European Union (EU), the African Union (AU), or the Economic Community of West African States (ECOWAS). The legality of such sanctions is particularly contentious where they are adopted without explicit UNSC authorisation.
International organisations are creatures of treaty law and possess only those powers conferred upon them by their constituent instruments. Consequently, where a regional organisation imposes sanctions on its own members pursuant to its founding treaty, such measures may be legally justified. However, the legality of sanctions imposed on non-member States is far more uncertain and often disputed.
A further complication lies in the terminology itself. While sanctions adopted by groups of States are sometimes labelled “multilateral,” they may still be considered “unilateral” in a legal sense if they lack universal or UNSC authorisation. The increasing use of such sanctions has partly been attributed to political deadlock within the UNSC, particularly the exercise of veto powers by the permanent members, which has prevented collective action in certain situations.
Arguments in Defence of Unilateral Economic Sanctions
Proponents of unilateral sanctions argue that no clear rule of international law expressly prohibits them. The UN Charter does not deprive States of their sovereign right to regulate economic relations, and not all coercive economic measures amount to unlawful intervention. Moreover, while several United Nations General Assembly resolutions such as Resolutions 2131, 2625, 3201, and 3281 condemn unilateral economic coercion, these resolutions, in the legal nature of resolutionare not legally binding and do not, in themselves, create enforceable obligations.
It is also difficult to assert that a rule of customary international law has crystallised prohibiting unilateral economic sanctions. Although many developing States oppose such measures, consistent and general State practice accompanied by opinio juris is lacking, particularly given the persistent opposition of many Western States. In addition, international law recognises the right of States to adopt countermeasures and acts of retorsion, which may legitimately take economic form.
Humanitarian and Political Implications
Despite these legal arguments, unilateral economic sanctions often operate less as legal enforcement tools and more as instruments of political power. In practice, such sanctions frequently produce severe humanitarian consequences, disproportionately affecting civilian populations rather than political elites. In extreme cases, they may contribute to widespread violations of economic and social rights which have been codified as a fundamental obligation of states in their municipal laws, for example, Chapter 2 of the 1999 Constitution of the Federal Republic of Nigeria. These realities underscore the need for a more principled and transparent legal framework governing the use of economic sanctions,
Way Forward
First, there is a pressing need for greater legal clarity through the development of internationally agreed rules on unilateral economic sanctions. Such rules could delineate the circumstances under which sanctions are lawful, the limits imposed by humanitarian considerations, and the procedural safeguards required to prevent abuse.
Secondly, meaningful reform of the United Nations Security Council remains essential. The concentration of veto power in the hands of the five permanent members has often paralysed collective action, prompting States and regional organisations to resort to unilateral measures. While comprehensive reform remains politically challenging, greater transparency, accountability, and representativeness within the UNSC could reduce reliance on legally questionable sanctions.
Conclusion
Unilateral economic sanctions occupy a complex and contested space in international law. While they are not per se unlawful, their legality depends on strict conditions relating to sovereignty, non-intervention, proportionality, and State responsibility. In practice, however, such sanctions frequently reflect political interests rather than principled legal enforcement and often impose severe burdens on civilian populations. A more coherent legal framework, coupled with institutional reform at the global level, is necessary to ensure that economic sanctions serve the objectives of international law, justice, equality, and the maintenance of international peace and security, rather than the unilateral interests of powerful States.
About the Author
Muhammadjawad Oloruntoyin is a 500 Level Law student at the Usmanu Danfodiyo University Sokoto.
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