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International law after the war of Ukraine: Towards the post-bellum accountability

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Katarína Šipulová

Katarína Šipulová

A fellow of the Oxford Global Society and Head of the Judicial Studies Institute, Masaryk University

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The views expressed are solely those of the author (s) and not of Oxford Global Society.

This article discusses how and why we need to prosecute the Russian invasion and subsequent war crimes committed in Ukraine under the framework of International law. It follows up on a commentary in a linked article: International law after the war of Ukraine: The Crumbling Cascade, which focuses on the reconstruction of the United Nations Security Council voting system in the face of ius cogens violations.

The war in Ukraine is by far not the only example of a superpower violating core principles of international law. However, the crudity with which an open aggressive war trespasses on the core grounding principle of the United Nations has raised questions about how to prosecute war crimes or the crime of aggression, as well as magnified long-existing challenges and discussions on how to reform and restructure the whole system.

What prosecutions does international law allow?

From the very beginning of the war, the eyes of the international legal community have turned to the Hague, to the International Criminal Court. The ICC is a permanent tribunal set up in 2002 with unprecedented authority to try perpetrators, irrespective of their political immunities, of the worst of international crimes: genocide, crimes against humanity, war crimes and, last but not least, from 2011 also the crime of aggression.

The jurisdiction of the International Criminal Court is unfortunately complicated by the fact that neither Russia nor Ukraine has ever ratified the Rome Statute. Russia withdrew its signature in 2016, soon after the ICC declared that Moscow can be held accountable as an occupying force in Crimea following the 2014 annexation. Ukraine, partly due to complex and difficult negotiations surrounding the recognition of the crime of aggression, also did not ratify the Rome Statute; however, it issued an ad hoc recognition of ICC jurisdiction in 2014 and in 2015 prolonged it indefinitely. This in turn means that the ICC has authority to investigate and prosecute crimes against humanity, war crimes (i.e. violations of the above-mentioned principles of humanitarian law including the Geneva conventions), as well as the crime of genocide. The situation is more complicated concerning the crime of aggression, which I discuss in the following section.

For the ICC, whose legitimacy has been much discussed in the past decade (here, here, or here), i.a. also for its selectiveness, inability to engage major powers, or slow reaction to the past escalation of violence between Russia and Ukraine,  the investigation of the situation in Ukraine represents an opportunity to redeem its role in ending the impunity and establishing the rule of law. For what it is worth, the ICC responded to the Russian invasion with atypical swiftness. Only days into the invasion, Prosecutor Khan announced that he would open an investigation into possible crimes committed in Ukraine under Russian aggression, eventually launching the investigation in early March 2022. It is also worth noting that the situation in Ukraine has been referred to the Chief Prosecutor by 43 individual member states. Interestingly, the investigation will focus on any allegations of war crimes, crimes against humanity or genocide committed on any part of Ukraine by any person from 21 November 2013 onwards. If the office of the Prosecutor gathers sufficient evidence, it will be able to request the ICC judges to issue arrest warrants or summonses and proceed with prosecutions.

Yet, the prosecution of these crimes is far from straightforward. Neither Ukraine nor Russia is a member party to the 2008 Convention on cluster munitions. The investigation and prosecution of war crimes requires not only evidence that these weapons have been used, but also a detailed analysis of how they were used, what their official targets were, whether they allowed one to distinguish between civilian and war targets. Although the accumulating evidence of civilian victims, sexual violence and other atrocities, combined with Putin’s long track record of territorial claims and contestations of the existence of Ukrainian nationality and sovereignty, prompted discussions of potential acts of cultural and ethnic genocide, substantively, it will be rather difficult to prove them.

Another challenge is presented by the attempt to hold top Russian state officials to account. We have past experience of the prosecution of presidents and highly positioned politicians (processes with al-Bashir and Charles Taylor), however, it is incredibly difficult to collect evidence on war crimes demonstrating the direct accountability of the political or military leadership of states – and particularly so during the ongoing conflict. The realistic probability of the ICC trying Putin or Lavrov before the war ends or before Putin loses his power is very bleak. It is also quite unlikely that the investigation of or eventual arrest warrants issued against Putin or Lavrov will produce a game-changer and deter further war operations by Russia. On the other hand, as was recently pointed out by Hillebrecht, the investigation initiated by the ICC, as well as by multiple national courts, can without doubt help to delegitimise Russia’s regime, signal human rights transgressions and increase the pressure on the international community further to isolate Russia and hold her accountable. Last but not least, indictments and warrants will also render the option of foreign exile for Putin or Lavrov in the event of Russia’s defeat rather difficult.

Can international law respond to the crime of aggression?

Compared to war crimes, crimes against humanity or genocide, it is much easier to prove the crime of aggression and Putin’s accountability, particularly given the relatively clear rules of the UN Charter as well as the speedily delivered orders of the ICJ and the ECtHR. The events of 24 February 2022 have been labelled a textbook example of the act of aggression; however, the question is how to prosecute it. Article 8bis of the Rome Statute defines the crime of aggression as “the planning, preparation, initiation or execution, by a person in a position effectively to exercise control over or to direct the political or military action of a State, of an act of aggression which, by its character, gravity and scale, constitutes a manifest violation of the Charter of the United Nations”. Para. 2 then defines the act of aggression as “the use of armed force by a State against the sovereignty, territorial integrity or political independence of another State, or in any other manner inconsistent with the Charter of the United Nations”.

Yet, the ICC exercises jurisdiction over a crime of aggression only if the crime was committed by a State Party to the Rome Statute. Although Ukraine accepted the ICC’s jurisdiction by the ad hoc resolution, this resolution does not empower the ICC to engage with the crime of aggression committed by Russia. Such authority would require either ratification by both countries or a referral by the Security Council. Obviously, neither scenario is realistic, prompting proposals for a substantive change of the Rome Statute which would give the ICC jurisdiction over acts of aggression committed by non-state parties, or bestow the power of referral on the General Assembly. However, the prevailing interpretation is that the General Assembly lacks the necessary coercive power that could create a foundation for the ICC’s authority.

The short-term debate on the other hand focuses on the identification of alternative platforms and judicial authorities that can potentially prosecute Russian aggression. The scholarly discussion initiated by a wonderful piece penned by Tom Dannenbaum has so far identified four different options:

  1. The establishment of an ad hoc international tribunal,
  2. The establishment of a hybrid tribunal under the auspices of the Council of Europe,
  3. The prosecution of aggression by a domestic court exercising territorial jurisdiction, or
  4. Prosecution by a domestic court exercising the universal jurisdiction.

Each of these options comes with certain costs and benefits. For domestic prosecutions, it is worth noting that the act of aggression is clearly criminalised under the Ukrainian, Belarussian, Russian and many other national criminal codes. Using existing domestic courts would come with little additional cost. Moreover, in principle, Ukraine’s judiciary enjoys primacy in addressing crimes against Ukrainian citizens, while international tribunals play (or should play) a complementary role. However, the Ukrainian judiciary will most likely still be paralysed in the coming months and the criminalisation of the aggression in Russia or Belarus is less than a dead letter until an eventual change in their political regimes or at least leadership (and, unfortunately, we know that autocratic regimes transition more often to different non-democratic regimes than to democracies, so the cooperation of new political establishment might still be questionable).

Komarov and Hathaway recently warned against the drawbacks of relying entirely on domestic courts. First, it is difficult to imagine that the Ukrainian judiciary will be structurally and financially ready to run such a high-profile prosecution. Second, the Ukrainian constitution (or its interpretation offered by the Ukrainian Constitutional Court) precludes the installation of a special domestic court. Third, although regular Ukrainian courts have in the past demonstrated the capacity to adjudicate on the complicity of individuals in crimes of aggression (such as in the case of 2019 ruling against former president Yanukovych), in absentia trials of this level of importance often lack sufficient legitimacy and their enforcement lies completely out of the hands of the Ukrainian authorities – or other domestic courts of third countries.  

An interesting alternative would be prosecution by a court of a different country. At least 74 states around the world recognise the crime of aggression, and since the start of the invasion, domestic courts in 9 countries have simultaneously initiated prosecutions. Some of these countries have vast resources, yet they will still have to grapple with Putin’s immunity, at least until Russia is defeated and Putin loses his position as President. Although there are already thousands of active domestic investigations, generally these would have to face very similar enforcement struggles to potential trials by Ukrainian judicial authorities.

With domestic judicial means foreclosed, the establishment of an ad hoc international tribunal for the crime of aggression would have the benefit of direct UN authorisation and will be endowed with the legal power to request the cooperation of third countries when collecting evidence or executing judgements. An additional argument for delegating the prosecution of war crimes and a crime of aggression at an international level is the logic of the Nuremberg and Tokyo trials and their established legacy that the gravest of crimes should be tried by international bodies as they concern humanity and the international system as such. This justification is particularly valid for the prosecution of Russia’s aggression towards and invasion of Ukraine.

No wonder that the establishment of a special international tribunal has been supported by a plethora of international scholars. Apart from pragmatic benefits, the international tribunal would also send a powerful message of the international community’s commitment to UN Charter principles and its refusal to tolerate both Russia’s actions and the existence of aggressive war as such.

Yet, there are also some limits to a potential ad hoc tribunal. Given Russia’s veto power in the Security Council, the most probable scenario is that the tribunal would be established by a resolution of the UN General Assembly or by a treaty between Ukraine and the UN. Yet, the mandate of a tribunal established by the General Assembly is considerably weaker than that of one that would have the authorisation of the Security Council as it has a rather limited ability to require the cooperation of other countries or to remove personal immunities of government officials. Moreover, international ad hoc tribunals forced upon countries by the international community (such as, e.g., the International Criminal Tribunal for Rwanda) have historically struggled with criticisms of selectiveness (in the identification of victims and perpetrators), as well as with the ability to deliver effective justice. Some experts even argue that it is unreasonable to expect the very same world powers that neutralised the ICC’s capacity to prosecute aggression, suddenly to agree to establish a completely new separate and costly tribunal that would be endowed with powers to prosecute non-state parties for the crime of aggression. 

Lastly, taking into consideration these potential limits, costs and doubts about the added value of a new international ad hoc tribunal compared to the existing ICC, Kevin Jon Heller has proposed the establishment of the Extraordinary Ukrainian Chamber for Aggression, a hybrid tribunal that would be part of the Ukrainian judicial system created under the auspices of the Council of Europe and its Committee of Ministers. Compared to on the UN, reliance on the Council of Europe would help rid the tribunal of the risk of Russia executing its veto power, as the Committee of Ministers on 16 March 2022, in an unprecedented step, expelled Russia from the Council of Europe. According to Heller, the setting of the tribunal within a European organisation would bring several benefits, including the ability to take advantage of EU EuroJust’s Joint Investigation Team, minimising the costs of establishing a new unit, as well as the elimination of controversies tied to the concept of universal jurisdiction. It would also lend the tribunal credibility and reliance on a strong regional organisation with by far the most efficient and most advanced human rights monitoring system. On the other hand, it is worth noting that with Russia expelled from the Council of Europe, the establishment of a regional international tribunal to prosecute a non-member state would not come free of controversies similar to universal jurisdiction disputes.

Why do we need to address the crime of aggression?

On 25 February 2022, just a day after the Russian army invaded Ukraine, Russia vetoed the UN Security Council resolution denouncing the invasion of Ukraine, effectively halting any further engagement of the Security Council in the conflict.

The early April parliamentary elections in Hungary and strengthened alliance between Vladimir Putin and Viktor Orbán, re-elected for the fourth time as the Hungarian prime minister, cast serious doubts on the presumed ability of the Council of Europe unanimously to support the prosecution of the crime of aggression in Ukraine.

The international community has an indisputable moral, political and legal obligation to act in prevention of any further atrocities. Yet, the inability of international political authorities to act due to the setting up of veto powers inside the UN Security Council shifted the major part of the burden on to judicial bodies. The war in Ukraine however cannot be judicialized and international law cannot help Ukraine to win it.

What international law can do, on the other hand, is to help set a clear, compelling precedent showing that the international community will not tolerate an aggressive war. From this perspective, the ability of international law to address the crime of aggression precedes the prosecution of crimes under humanitarian law and various individual human rights violations.

The war in Ukraine is but one of many examples demonstrating how inadequate the existing international legal and political order is to respond to the act of aggression. The founding principle of the UN Charter has been shaken to its core, the gridlock of the Security Council casts doubts on its future destiny, treaty commitments have significantly lost their credibility and the debate calls for re-evaluation of who should watch over the guardians of the international order. The political deadlock also impacts on judicial authorities: the ICC seeks to regain new relevance; any other judicial bodies either lack sufficient legitimacy or formal powers to prosecute sitting heads of state.

The answer to how the international criminal law should respond to the war in Ukraine therefore needs to form a clear, logical and convincing precedent regarding how the world should respond to any future repetitions of acts of aggression. The Russian invasion was by no means the first nor the last example of the unjustified use of force by a world superpower. However, due to the overwhelming international response and public pressure, it offers a unique opportunity to offer unsettling answers to some of the challenges it presented both to the United Nations and the dependence of international criminal bodies on the cooperation of world superpowers. If the international community fails to take part in this prosecution and instead relies on domestic or other ad hoc regional tribunals taking on the burden of the responsibility to deliver justice, the international system, the justice cascade and the core UN Charter principle of non-aggression will crumble and lose any credibility.