Sanctions are a tool used by some states in their international relations, often to protect their interests or to prevent or respond to an illegal act that may be committed by another state or group. There is no single definition of a sanction, and the term is used in many different contexts. They usually involve trade sanctions (such as embargoes), asset freezes or travel bans, but can also include a much wider range of economic or legal measures.
Sanctions, and seizing assets, in context
Some states have been seeking to seize Russian assets as a way to help Ukraine, following Russia’s full-scale invasion in February 2022. This call to seize assets has revived legal questions that go to the heart of fundamental principles of international law. It has reignited debates over the legality, legitimacy, and efficacy of groups of states taking their own measures to maintain or restore international peace and security.
This briefing provides a detailed overview of the context and law relating to unilateral sanctions, as well as the political and legal developments leading to the possible seizure of Russian assets to aid Ukraine.
International law relating to sanctions
The use of sanctions by states, particularly outside of the framework of the United Nations Security Council, has a complicated relationship with international law. Depending on the measures adopted by a state, sanctions could be an entirely legal exercise of its sovereignty or a potentially unlawful breach of international law that would require some justification.
Whether unilateral sanctions need to be justified at all is also the subject of considerable debate in the international community, with divisions over this issue evident during meetings at the UN General Assembly. This briefing outlines some of the positions in those debates, and tracks the voting patterns of related Assembly resolutions.
The legal framework that applies to states adopting their own sanctions in international law is complex, dynamic and still very unsettled. There are numerous factors that make it difficult to be certain about whether particular measures are compatible with international law, or on what precise legal basis they might be justified. There is no single international treaty dealing with sanctions and when states may or may not adopt restrictive measures of this kind. Some rules that may restrict these actions are split between different sources of international law, including treaties and customary international law. Customary international law is a source of rules of international law that are not formally written in treaties. They are established based on evidence of custom that states accept as law.
This means that what states say and do, and their belief that their actions amount to a right or obligation, can indicate the status of international rules if the practice is sufficiently clear. Therefore, the historical context of state’s approaches to international sanctions is relevant not only because of the development of policy and political positions, but also in indicating the relevant evidence of whether there is any settled practice and acceptance of customary rules that apply to sanctions. The debates at the UN General Assembly outlined in this briefing provide some context in that regard to understand whether there is a lack of consensus on some core legal issues.
There are several possible international obligations that could be engaged when states impose unilateral sanctions, including:
- The principle of non-intervention (the right of states to conduct domestic affairs without outside interference)
- The principle of sovereign equality of states, and the rules relating to state immunity (from the jurisdiction of foreign courts)
- Obligations under the rules of the World Trade Organization (WTO)
- Obligations under bilateral investment treaties, or the customary international law rules relating to the treatment of foreign investors, including:
- Fair and equitable treatment standards
- The prohibition of expropriation (without compensation), where the state confiscates property
But, there are also potential justifications for a state imposing sanctions, including:
- The doctrine of countermeasures under the law of state responsibility, where a state can take otherwise unlawful measures against another state that has acted unlawfully
- Security exceptions provided for in WTO agreements or bilateral trading treaties
- Recent arguments on the applicability of the right of self-defence when taking measures short of military force.
The debate on countermeasures
The doctrine of countermeasures has been a focus of recent international legal discussion, particularly as it applies to some states’ plans to confiscate Russian state assets to fund the reconstruction and recovery of Ukraine.
If a state has been injured by another state’s breach of international law, it can take countermeasures. These allow the state to temporarily take measures that would normally be unlawful to induce the wrongdoing state to stop its unlawful behaviour and make good on its breach of the law.
The doctrine is part of the customary international law rules on state responsibility for internationally wrongful acts. These rules determine what happens when a state breaches international obligations and the possible justifications for doing so. These rules are outlined in the International Law Commission’s Articles on the Responsibility of States for Internationally Wrongful Acts (ILC Articles / ARISWA), adopted by the UN General Assembly in 2002.
There are several unsettled legal questions around the doctrine of countermeasures. For example, it is still unclear in international law whether the doctrine of countermeasures applies to the growing pattern of states imposing unilateral sanctions. The main reason for this is that states adopting unilateral sanctions generally do not justify the legal basis for their use of these measures.
Several specific legal issues also remain unresolved, including whether states who are not directly injured by a breach of a wrongdoing state can take countermeasures in the general interest. This issue has become particularly relevant in light of sanctions taken against Russia after its invasion of Ukraine.
Seizing Russian assets
The growing calls to seize (rather than freeze) Russian assets in response to Russia’s full-scale invasion of Ukraine in February 2022 have focused on many of these legal rules and debates around the ability of states to adopt certain types of sanctions.
Some have cited the doctrine of countermeasures as the legal basis supporting calls to seize Russian assets. For example, in April 2024, the Council of Europe’s Parliamentary Assembly unanimously adopted Resolution 2539 called for states to seize Russia’s state assets, including the assets of “Russian politicians, propagandists, oligarchs, and other war collaborators”. The resolution supported “the recourse to countermeasures, as outlined in the framework of international law, to induce compliance by the Russian Federation with its international legal obligations and responsibilities”.
As well as debating particular legal issues in the application of countermeasures, some experts warn against stretching the doctrine of countermeasures too far, or argue that doing so would risk undermining the legitimacy of the international legal system.