To: The President of State A
From: Legal Advisor
Date: 15 October 2026
Re: Advice on the legality of actions taken by States B, C, and D
Introduction
This advice memorandum addresses the legality of certain actions taken by States B, C, and D in response to State A’s conduct concerning minority group X. The analysis will proceed in two parts. First, it will assess the legality of the reaction by States B and C, which involved returning people to State A and shelling industrial cities. Second, it will assess the legality of State D’s unilateral commencement of proceedings against State A at the International Court of Justice (ICJ). The advice is based on established principles of public international law.
The Legality of the Reaction of States B and C
States B and C have characterised their actions as a “response” to State A’s conduct. In international law, a unilateral response by a state to another state’s wrongful act may be classified as a countermeasure. For a countermeasure to be lawful, it must comply with strict conditions codified in the International Law Commission’s Articles on the Responsibility of States for Internationally Wrongful Acts (ARSIWA), which are widely regarded as reflecting customary international law (ILC, 2001). The actions of States B and C must be assessed against these rules.
The Shelling of Industrial Cities
The shelling of State A’s core industrial cities by States B and C constitutes a use of armed force. The foundational rule of modern international law, enshrined in Article 2(4) of the United Nations Charter, is the prohibition on the threat or use of force against the territorial integrity or political independence of any state. The only clear exceptions to this prohibition are self-defence under Article 51 of the Charter or when the use of force is authorised by the UN Security Council under Chapter VII.
In this case, State A has not conducted an “armed attack” against States B or C, which is the necessary precondition for the exercise of the right to self-defence (ICJ, 1986). Furthermore, there is no information to suggest that the UN Security Council has authorised this action. Therefore, the shelling can only be justified if it qualifies as a lawful countermeasure.
However, Article 50(1)(a) of ARSIWA explicitly states that countermeasures shall not affect “the obligation to refrain from the threat or use of force as embodied in the Charter of the United Nations”. This means that a state cannot resort to armed force as a response to another state’s wrongful act, no matter how serious that act is. The shelling of State A’s cities is a clear violation of Article 2(4) of the UN Charter and cannot be excused as a countermeasure.
Therefore, the campaign of shelling conducted by States B and C is an unlawful use of force and constitutes an internationally wrongful act.
The Return of Members of Minority X
The act of “returning people belonging to minority X to the area they inhabit in State A” must also be assessed as a potential countermeasure. Unlike the use of force, such an action is not absolutely prohibited. However, it must still satisfy the general conditions for countermeasures.
First, under Article 49 of ARSIWA, countermeasures may only be taken by an “injured State”. State B, into whose territory members of minority X have been transferred, is arguably an injured State as it is “specially affected” by State A’s breach of an international obligation (ARSIWA, Art 42(b)(i)). State C’s position is weaker, as it does not appear to be directly affected. While there is a debate about whether non-injured states can take countermeasures to protect a community interest, the law is unsettled. Article 54 of ARSIWA refers only to “lawful measures”, which is generally interpreted as not including countermeasures that would otherwise be unlawful (Crawford, 2013).
Second, even if taken by an injured state like B, a countermeasure must be proportionate. According to Article 51 of ARSIWA, countermeasures “must be commensurate with the injury suffered, taking into account the gravity of the internationally wrongful act and the rights in question”. Returning people, especially if done forcibly, may be seen as disproportionate.
More importantly, Article 50(1)(b) of ARSIWA provides that countermeasures shall not affect “obligations for the protection of fundamental human rights”. The forcible movement of people across a border against their will is a serious infringement of their rights, including the right to security of person and freedom of movement. Such an act would almost certainly be considered a violation of fundamental human rights. Therefore, even if intended as a countermeasure, the act of returning members of minority X by States B and C would be unlawful as it contravenes an obligation for the protection of fundamental human rights.
In summary, both components of the reaction by States B and C are illegal under international law.
The Legality of the Action by State D
In June 2026, State D commenced proceedings against State A in the ICJ for genocide. The legality of this action depends not on the substance of the claim at this stage, but on whether the ICJ has jurisdiction to hear the case.
The jurisdiction of the ICJ is based on the consent of the states involved. A state cannot be forced to appear before the Court. Consent can be given in several ways, but in a case brought unilaterally like this one, the most relevant basis would be a compromissory clause in a treaty to which both State A and State D are parties.
The claim concerns genocide, which is governed by the 1948 Convention on the Prevention and Punishment of the Crime of Genocide (the “Genocide Convention”). Article IX of this Convention provides that disputes between parties “relating to the interpretation, application or fulfilment of the present Convention, including those relating to the responsibility of a State for genocide… shall be submitted to the International Court of Justice at the request of any of the parties to the dispute.”
Therefore, if both State A and State D are parties to the Genocide Convention, Article IX provides a valid legal basis for State D to bring the case to the ICJ. The fact that State D is not an “injured” party in the traditional sense is irrelevant. The ICJ has confirmed that the obligations in the Genocide Convention are owed *erga omnes partes* – that is, they are owed by every state party to all other state parties. This means any state party has a right to bring a claim to ensure compliance (ICJ, 2020). In the case of *The Gambia v. Myanmar*, the Court affirmed that The Gambia had standing to bring a case against Myanmar for alleged genocide, despite not being directly affected.
State D’s action is therefore lawful provided that a basis for jurisdiction exists. The primary question for State A is a practical one: has it consented to the ICJ’s jurisdiction in this matter? To determine this, the following should be ascertained:
1. Is State A a party to the Genocide Convention?
2. If so, has State A made a reservation to Article IX of the Convention? Many states have made reservations excluding the ICJ’s jurisdiction. If State A has a valid reservation, the Court will lack jurisdiction on this basis.
3. Is State D a party to the Convention without a reservation that would prevent it from bringing a claim?
4. Separately, have both State A and State D made declarations accepting the ICJ’s compulsory jurisdiction under Article 36(2) of the ICJ Statute, and do these declarations cover this dispute?
If a basis for jurisdiction is established, particularly under the Genocide Convention, then State D’s unilateral commencement of proceedings is a lawful exercise of its rights under that treaty.
Conclusion
The advice to the President of State A is as follows:
1. The military and other actions taken by States B and C are unlawful. The shelling of cities is a violation of the prohibition on the use of force. The returning of people is an unlawful countermeasure because it violates fundamental human rights and is likely disproportionate. State A has strong grounds to protest these actions and seek remedies for them as internationally wrongful acts.
2. The action by State D in commencing proceedings at the ICJ is a legal procedure, not a hostile act in itself. Its legality turns on whether the ICJ has jurisdiction. This must be urgently determined by reviewing State A’s status and reservations concerning the Genocide Convention and its position regarding the ICJ’s compulsory jurisdiction. If jurisdiction is established, State A is obliged to engage with the proceedings.
References
- Crawford, J. (2013) State Responsibility: The General Part. Cambridge University Press.
- International Court of Justice (ICJ). (1986) Military and Paramilitary Activities in and against Nicaragua (Nicaragua v. United States of America), Merits, Judgment, ICJ Reports 1986, p. 14.
- International Court of Justice (ICJ). (2020) Application of the Convention on the Prevention and Punishment of the Crime of Genocide (The Gambia v. Myanmar), Provisional Measures, Order of 23 January 2020, ICJ Reports 2020, p. 3.
- International Law Commission (ILC). (2001) Draft articles on Responsibility of States for Internationally Wrongful Acts, with commentaries. In Yearbook of the International Law Commission, 2001, vol. II, Part Two.
- United Nations. (1945) Charter of the United Nations.
- United Nations. (1948) Convention on the Prevention and Punishment of the Crime of Genocide.
