Sovereign Equality or Equal Sovereignty

Fourteen years ago, the International Court of Justice, in Jurisdictional Immunities, affirmed State immunity even for cases of jus cogens violations or human rights abuses. Yet, victims of State-caused harm continue to bring civil claims against foreign States. These include Ukrainians who suffered damages caused by the Russian aggression, but also dissidents in exile who continue to be persecuted by their State of origin. However, their chances of securing financial compensation are slim. In practice, most domestic courts will deny jurisdiction over the claims because of State immunity.

State immunity is a procedural corollary of sovereign equality: One sovereign must not exercise jurisdiction over another sovereign. But what happens when sovereign equality is disrupted? Can a State that disregards the sovereignty of another demand respect of its own sovereignty?

Addressing this question, I highlight an observation from recent domestic judgments: The obligation to grant immunity to a foreign State was denied because the foreign State infringed on the forum State’s sovereignty. I discuss this controversial argument in the context of reciprocity in international law. My conclusion is that a State may be relieved from its obligation to respect a foreign State’s sovereignty regarding the conduct by which that foreign State has violated the forum State’s sovereignty. Last, I provide an outlook on whether this argument could aid victims seeking redress against a foreign State.

Reciprocal Respect for Sovereignty in Recent Immunity Judgments

Courts in several jurisdictions have begun to articulate a link between reciprocal respect for sovereign equality and jurisdictional immunity. They have allowed claims against foreign States and denied immunity where the foreign State has itself infringed upon the sovereignty of the forum State.

The Ukrainian Supreme Court formulates this argument clearly. In several judgments from 2022, the Court permitted civil claims against Russia for damage caused by acts of aggression. The court reasoned that State immunity is premised on reciprocal respect for sovereignty. It asserted that a State cannot wage an aggressive war and, at the same time and for the same conduct, claim the protection of its sovereignty before the courts of the victim State. Supreme Court Judge Pohribnyi provides a verbatim translation of the decision of his Chamber:

“that a necessary condition for compliance with the principle of international law regarding judicial immunity is the mutual recognition of state sovereignty by another country. So when the aggressor country denies the sovereignty of Ukraine and commits a war of aggression against it, there is no obligation to respect and observe the sovereignty of this country.”

On this view, sovereign equality is a reciprocal legal relationship which allows for the denial of immunity in response to a violation of sovereignty. The same line of reasoning appears in a 2025 judgment of the German Federal Court of Justice. The case dealt with the sabotage of the Nord Stream Pipelines, allegedly carried out by Ukrainian intelligence. The Court found this conduct to violate Germany’s sovereign right under the United Nations Law of the Sea Convention to lay pipelines. In the criminal law judgment concerning the functional immunity of a Ukrainian agent, the Court made a general finding on the rationale of immunity, not only for State agents but also for the State itself. The Court affirmed that immunity is granted to protect State sovereignty. Noteworthy, it contrasted that there is:

“no justification for such respect for State sovereignty in the case of covert State action, which in turn disregards the sovereign rights of another State under international law” [Author’s translation from German].

The United Kingdom Court of Appeal expressed a similar notion in 2024. The case concerned the harassment of a political dissident and interference with the territorial sovereignty of the United Kingdom. The Court’s reasoning linked immunity to reciprocal respect for sovereignty – albeit in more cautious terms:

“If State A interferes with the territorial sovereignty of State B […], it takes the risk that it will be subject to civil proceedings in State B.”

A Canadian Regional Court of Appeal’s decision concerning the terrorism exception to State immunity hints at the same argument. The judges acknowledge the obligation under international law to respect State sovereignty, including the sovereign right of States to protect their citizens. At the same time, they accept that the legislator may create exceptions to State immunity to enable redress for individuals as part of attacks on those sovereign-protective functions. Although not expressly framed in terms of reciprocity, the materials suggest a link between immunity and ‘mutual’ sovereignty by allowing individuals redress in response to attacks on sovereign functions.

Taken together, a possible exception to the general right to immunity emerges because State immunity is conditioned on reciprocal respect for sovereignty. A forum State’s court would need to assess whether a preceding violation of its sovereignty had occurred. What constitutes a relevant violation beyond the cases cited remains unsettled, leaving the assessment to the discretion of individual courts. By this reasoning, immunity may be denied where sovereignty is not respected. However, this argument has not yet crystallised into a consistent doctrine for denying immunity. None of the materials relies exclusively on the lack of reciprocal respect for sovereignty to deny immunity. It remains an underlying rationale rather than an articulated rule.

Immunity, Sovereignty and Reciprocity in International Law

As a procedural rule, immunity prevails regardless of the conduct’s substantive lawfulness. Therefore, arguments based on substance, such as violations of jus cogens norms or commissions of delicta imperii, have failed to create an exception to the obligation to grant immunity.

Framing the denial of immunity as a response to an unwelcome act also faces significant hurdles. It cannot be justified as retorsion, since retorsion is a lawful act that does not affect another State’s rights, while the denial of immunity itself violates the foreign State’s right to immunity. Arguments based on countermeasures are difficult to sustain because such measures are meant to induce compliance with an ongoing obligation. By the time a case reaches trial, however, the breach has usually already ended, and courts are unlikely to be the appropriate authority to call upon the foreign State to cease its infringement.

However, the mentioned judgments did not phrase the denial of immunity in such terms. Instead, the wording indicated that the obligation to grant immunity did not apply. This was because the rationale for granting immunity was not triggered, namely reciprocal respect for sovereignty.

The argument is straightforward. If State immunity is based on sovereign equality and sovereign equality is based on reciprocal respect, then State immunity is based on the reciprocal respect of State sovereignty. Yet, the doctrinal basis for the premises remains complex.

The first premise is easy to sustain: It is evident from the ICJ’s jurisprudence that State immunity “derives from the principle of sovereign equality of States”.

The second premise, that sovereign equality presupposes reciprocal respect, requires more explanation. The concept of reciprocity is well-established in international law: State A’s rights and obligations towards State B depend on the corresponding conduct of State B. This includes that State A can adjust its own conduct in response to a breach by State B.

The crucial point in the argument is the relationship between reciprocity and the sovereign equality of States. Reciprocity is a “necessary consequence” of the legal equality and sovereignty of States. This results in the State’s right to claim immunity from foreign jurisdiction but also in the corresponding obligation to grant immunity to another State.

But can this idea of reciprocity also be used inversely? Not as a consequence of sovereign equality but as a condition for the obligation to respect sovereign equality? The answer lies in the function of reciprocity: the interdependence of rights and obligations is a mechanism to maintain sovereign equality. In line with this, international law is no stranger to the idea that a State may be relieved of an obligation to respect another State’s rights in response to an infringement of its own. This can be illustrated with examples across different legal regimes: States can declare a diplomat, who violates their laws, persona non grata (Article 9 Vienna Convention on Diplomatic Relations) when their right to exercise adjudicative jurisdiction is barred because of the diplomat’s conventional and customary immunity. States may also take countermeasures (Articles 22 and 49 of the Draft Articles on the Responsibility of States for Internationally Wrongful Acts) and invoke security exceptions in trade agreements (Article 31 General Agreement on Tariffs and Trade 1947) in response to infringements of their own rights. These mechanisms do not require an exact correspondence of the suspension and violation but a mere nexus between them. They show that also the exemption from an obligation can serve to maintain sovereign equality. Against this background, it cannot be ruled out that state immunity may develop into a regime in which the obligation to respect sovereignty ceases if the respect is not reciprocal. As the judgments above show, this is an argument that courts currently discuss.

A New Path to Remedies Against Foreign States?

As international law centres on State sovereignty, prioritizing human rights and adopting a victim-centred perspective is challenging. In this context, the reciprocity-based argument of respect for sovereignty offers a potential tool for victims seeking redress against a foreign State. The argument works within the classical framework of international law: It focuses not on the violation of individual rights but on the infringement of the forum State’s sovereignty. Victims could rely on it if they can show that the violation of their rights also infringed upon the forum State’s sovereignty. This may include victims of aggression, victims of sabotage acts, or exiled dissidents mistreated on the territory of the forum State.

However, the argument and the recent engagement with it do not change the current possibilities for victims to obtain redress from a foreign State. State immunity rules, as norms of customary international law, can only develop over time. Any change must be based on widespread and consistent practice in denying immunity for claims relating to infringements of the forum State’s sovereignty. It may not be likely that States will limit the scope of immunity in the near future. Still, the topic of State immunity is in constant flux, and this trend is worth monitoring.