UKRAINE'S PUSH TO PROSECUTE AGGRESSION IMPLICATIONS FOR IMMUNITY RATIONE PERSONAE AND THE CRIME OF AGGRESSION.

• Author: Hamilton, Rebecca
• Position: Russia, Ukraine

ABSTRACT

Russia's aggression against Ukraine dates back to its 2014 annexation of Ukraine's southern peninsula, Crimea. (1) It was Russia's brazen full-scale invasion of Ukraine on February 24, 2022, (2) however, that captured global attention and put the crime of aggression--the resort to war in violation of the UN Charter (3) --in the spotlight.

In recent months, model indictments of Russian President Vladimir Putin, (4) as well as Foreign Minister Sergei Lavrov, Defence Minister Sergei Shoigu and others, have been widely publicized. (5) A 2010 amendment to the Rome Statute of the International Criminal Court means that the ICC now has jurisdiction over the crime of aggression when there is state consent. (6) But Russia has not--and will not--provide such consent. If an aggression indictment is to be formally issued, it will need to come through a newly created tribunal. (7)

Just a week after Russia's February 24 invasion, Chatham House convened a high-profile declaration to support the establishment of a tribunal to prosecute aggression. (8) The following month, Ukrainian President Volodymyr Zelenskyy used his address to the UN Security Council to call for the creation of an aggression tribunal. (9) Since then, the Ukrainian government has been working with willing governments in Europe on plans to bring such a tribunal to life. (10)

Historically, powerful states have been reticent to let international criminal law encroach on decisions about the use of force. (11) So, the plans currently being developed may ultimately be blocked by the self-interest of states--the United States among the forefront--in fear of the precedent an aggression tribunal would set. Indeed, this is the most likely outcome. But, as yet, the U.S. at least has not publicly registered any such dissent. (12) Moreover, Russia's invasion seems to have pushed states out of business-as-usual positioning in all manner of ways. (13) Therefore, it remains at least a possibility that such a tribunal will be established. (14) If it is, and especially if it issues indictments, this will have significant implications for the development of international law, regardless of whether those accused are ever arrested and brought to trial. (15)

The first implication, which forms the bulk of the following analysis, relates to the law on head of state immunity. (16) The establishment of an aggression tribunal that enables the indictment of Putin or Lavrov while they remain in their existing roles will constitute, in Rebecca Ingber's terminology, an "interpretation catalyst." (17) The tribunal's establishment will trigger legal interpretations by states on the topic of immunity ratione personae. (18) This will contribute to state practice and opinio juris, regardless of whether the tribunal pursues indictments or ever brings any accused into custody. If a case ever does proceed, the tribunal's decision on the immunity challenge that these defendants would inevitably bring, would further contribute to our understanding of this fraught area of international law. (19)

The second implication relates to our understanding of the scope of liability for the crime of aggression. Aggression is understood to be a leadership crime. (20) But the charging decisions made by the aggression tribunal will add granularity to this understanding. (21) There is a meaningful difference, for example, between charging Putin alone, or charging him together with 15 members of his national security or military leadership. (22)

Finally, the temporal jurisdiction laid out in any aggression tribunal's constitutive document will influence, albeit indirectly, our understanding of the scope of the crime of aggression. (23) A temporal jurisdiction clause that begins on February 24, 2022 will prevent a tribunal from considering acts short of full-scale invasion. (24) This does not mean, of course, that Russia's acts of aggression prior to February 24, 2022 do not constitute aggression, (25) however, it does set the bar very high for the future engagement of international criminal law with the crime of aggression. If a case on these grounds proceeds, the first jurisprudence on aggression since Nuremberg will be limited to this textbook example. (26)

TABLE OF CONTENTS ABSTRACT TABLE OF CONTENTS I: IMMUNITY RATIONE PERSONAE A. ICJ Arrest Warrant Case B. Customary International Law C. Models of an Aggression Tribunal II: Scope of Liability for Aggression III: Scope of the Crime of Aggression CONCLUSION I: IMMUNITY RATIONE PERSONAE

Courts seeking to prosecute foreign state officials need to be concerned with two broad types of immunities. The first, immunity ratione materiae, (27) or functional immunity, provides lasting immunity to state officials for official acts they performed in their position. (28) The second, immunity ratione personae, (29) provides immunity to certain high-level officials who represent the state, such as heads of state and foreign ministers, but only for the period in which they hold their official position. (30) Unlike functional immunity, immunity for certain high-level officials covers all acts, including private ones and ones committed prior to holding office. (31)

There is broad agreement that functional immunity is not a bar to the prosecution of serious international crimes, even in foreign domestic courts. (32) Yet, for as long as certain high-level officials remain in power, immunity ratione personae continues to protect them. (33) This long-standing aspect of immunities law flows from the sovereign equality of states, par in parent non habet imperium. (34) The immunity exists so that one state cannot sit in judgment of another. (35) As such, the immunity is not held by the head of state as an individual, but by the state itself. (36)

Exactly which state officials immunity ratione personae applies to is subject to some debate. (37) The following analysis, however, proceeds on the generally accepted view that as President and Foreign Minister respectively, Putin and Lavrov would have robust claims to immunity ratione personae should a domestic court outside of Russia try to prosecute them. (38) The issue becomes more complex however, once one moves beyond foreign domestic courts.

1. ICJ Arrest Warrant Case

   The foundational language on this issue comes from the International Court of Justice decision in the Arrest Warrant case of 11 April 2000. (39) The ICJ agreed with the Democratic Republic of Congo that its incumbent foreign minister had immunity from arrest for international crimes with respect to Belgian judicial proceedings. (40) It nonetheless offered assurance that such immunity did not equate to impunity. (41)

   The ICJ noted, uncontroversially, that senior officials could be prosecuted in their home state, in foreign states if their home state waives immunity, or once they leave office. (42) For as long as Putin retains power in Russia, all of these pathways to prosecution remain closed. The Court, however, also provided a fourth pathway that is potentially relevant to Russia's aggression against Ukraine. (43) It stated that "an incumbent or former Minister for Foreign Affairs may be subject to criminal proceedings before certain international criminal courts, where they have jurisdiction." (44)

   The Court offered three non-exclusive examples of such international courts: the two extant ad hoc tribunals, the International Criminal Tribunal for the former Yugoslavia and the International Criminal Tribunal for Rwanda, established by the UN Security Council pursuant to Chapter VII of UN Charter, and the yet-to-be-operational International Criminal Court. (45) Each of these courts, with their statutory provisions denying immunity, hold a direct source of authority for a state waiver of immunity. (46) In the case of the ad hoc tribunals, this source was the binding force of the UN Security Council's Chapter VII authority; (47) for the ICC it is state consent by parties who join the court's treaty. (48)

   For the reasons outlined above--Russia's veto-wielding seat on the UN Security Council, (49) and Russia's lack of consent to ICC jurisdiction (50)--these sources of authority will not be available to any aggression tribunal. (51) As a result, states considering the establishment of an aggression tribunal will have to wade into a legal evaluation of whether the ICJ's category of "certain international criminal courts [with] jurisdiction" (52) includes a tribunal without a direct source of authority to waive immunity and, if so, what the required attributes of such a tribunal would be.

2. Customary International Law

   In the years since the ICJ Arrest Warrant decision, different international criminal judgements, (53) and much scholarship, (54) have grappled with the question of what characteristics an international criminal court must have in order to render immunity ratione personae inapplicable. (55) Space constraints preclude detailed description, but beyond the uncontroversial although here-inapplicable examples of state immunity being waived by consent or over-ridden by the UN Security Council under Chapter VII, it is possible to distill arguments about whether customary international law permits courts with international jurisdiction to prosecute a sitting head of state or foreign minister without violating immunity ratione personae. (56)

   Returning to foundational principles, recall that immunity ratione personae exists to uphold the principle par in parem non habet imperium, that one sovereign state cannot exercise jurisdiction over another sovereign state. (57) It follows then that any international court in which immunity ratione personae is inapplicable must be exercising something other than sovereign jurisdiction. This makes the presence of international jurisdiction essential. But if international jurisdiction circumvents the need for a direct source of authority to waive immunity, it becomes critical to determine what exactly gives a court...