Michelle Coleman is a Lecturer in Law at Swansea University.

On 24 February 2022, Russia launched a widescale invasion of Ukraine resulting in an ongoing armed conflict. Since that date, numerous sources have been quick to call for the investigation and possible prosecution of international crimes arising out of the conflict. These calls to action open questions about whether international criminal law is an appropriate tool during armed conflict and what investigation and prosecution might be able to accomplish.

International Criminal Law is a legal system designed to prosecute international crimes. General categories of international crimes include aggression, genocide, war crimes, and crimes against humanity. These crimes are defined by customary law and the International Criminal Court, although the specific range of international crimes available can vary and depends on the particular jurisdiction that is engaging in the prosecution. Russia has already been publicly accused of aggression for their invasion; however, this alleged crime is unlikely to be prosecuted due to jurisdiction issues. Beyond the possibility of aggression as an initial potential crime, other international crimes may or may not be committed during the conflict. The existence of armed conflict is not by itself a crime.

International crimes can be prosecuted in four ways. The first is that the states involved can prosecute international crimes committed within their borders or by their citizens. This requires the state to have the capacity and willingness to prosecute these crimes, which is unlikely while conflict is ongoing and often difficult even after conflict has ended.

Alternatively, third-party states can prosecute international crimes through universal jurisdiction. This is relatively rare but not impossible, and several high-profile international cases have been tried through this process. It requires the third state to have the international crime within their criminal statute, and usually the suspect(s) must be within the territory of the third state in order to attend and participate in trial.

If a state is unwilling or unable to prosecute international crimes and the allegation is grave enough, the International Criminal Court might prosecute. Their jurisdiction is limited to crimes committed by or within the territory of member states. In the current context, it is important to note that neither Russia nor Ukraine is a member state, but Ukraine has availed itself of the jurisdiction of the Court for crimes committed from 2014 onward.

Finally, an ad hoc tribunal might be established to investigate and prosecute international crimes arising from the situation. The International Criminal Tribunal for the former Yugoslavia, International Criminal Tribunal for Rwanda, and Extraordinary Chambers in the Courts of Cambodia were created in this way. This is extremely unlikely to happen in the current situation, however, because firstly, the International Criminal Court is meant to obviate the need for ad hoc solutions, and secondly, the creation of these courts requires the agreement of the Security Council, of which Russia is a permanent member with veto power. While these four options exist and are possible, all the alternatives are unlikely while active armed conflict is ongoing. This is because criminal law is reactive, rather than proactive, in nature.

Unfortunately, there is no mechanism within international criminal law to directly prevent these crimes, or armed conflict, from happening. Rather, international criminal law is designed to end impunity—that is, to hold those who have committed international crimes responsible for crimes that have already occurred. Thus, international criminal law is mainly backward-looking and focused on providing accountability for events that have already happened. There is, however, some opportunity for deterrence as a result of engagement with international criminal law. Deterrence seems to be what these calls for investigation and prosecution are trying to accomplish. By calling on states or the International Criminal Court to investigate the situation, a statement is made that the world is watching and that potential perpetrators of international crimes will not be protected, international crimes will be investigated, and prosecutions will occur as appropriate. This threat of prosecution would ideally prevent Putin, and others, from committing these kinds of crimes during the course of the conflict.

There is evidence that some deterrent effect can come from ensuring that people know the situation is being monitored; however, it is slight. Specific deterrence in criminal law works best when there is a high likelihood that the would-be perpetrator will be caught doing the illegal act and there is a threat of certain and immediate punishment once they are caught. These, however, are not strengths of international criminal law. For international criminal law to be effective it must involve full investigation, a fair trial, and proof to the high criminal standard. This is to prevent sham prosecutions or victor’s justice from occurring and to ensure that those held accountable are actually responsible for the crimes they are accused of committing. Despite threats of prosecution, there are no guarantees that the perpetrators will be caught, and there almost certainly will not be quick punishment. However, even if deterrence was likely to work in international situations, it is cold comfort to those involved as they are still living with active armed conflict.

These calls for action are also specifically calling for investigations to begin, which is challenging under the circumstances but may be more successful than deterrence. Investigation is part of what makes international criminal law such a time-consuming process. Investigation into international crimes requires both agreement and capacity. There is no one group tasked to investigate these crimes. Although the prosecutor of the appropriate court leads the investigative activities, there is no international police or investigative force to carry out the day-to-day investigative tasks. So investigations in the course of international criminal justice necessarily require some cooperation of the states or individuals involved, at the very least to give access to potential evidence. The International Criminal Court has a limited number of non-staff professional investigators who can assist in investigation, but much of the evidence collection depends on non-governmental organizations, intermediaries, and direct cooperation of the government of the state(s). Third states or new ad hoc institutions that might engage in investigation and prosecution may have even more difficulty in having access to information and evidence. In addition to a lack of resources, capacity might be further hindered during active conflict because of the danger involved to those investigating or cooperating.

While Ukraine’s availing itself of the International Criminal Court’s jurisdiction implies that the state would be willing to cooperate with an international investigation, it is likely that they currently have limited capacity to assist while the conflict is ongoing. This is because resources that might be allocated to investigation and evidence gathering may be better used for defense at the moment. Further, the International Criminal Court has a responsibility to investigate all crimes occurring in the context of the conflict, meaning that Ukrainians could also be subject to scrutiny. A fear of seeing Ukrainian citizens prosecuted could also dampen enthusiasm for fully cooperating with the Court. Meanwhile, Russia is extremely unlikely to agree or cooperate with an investigation, regardless of whether there is an ongoing conflict. This will prevent access to evidence that might be held by Russia’s government or actors and may make evidence gathering from Russia very difficult, regardless of how much capacity they might have.

However, as noted above, investigation is not only reliant on the participation of states. Non-governmental organizations, researchers, and others can collect evidence contemporaneously to the conflict situation and be ready to look for potential crimes as they occur. Significant evidence gathering and preservation can occur in real time, and some organizations, notably PILPG (the Public Law & International Policy Group), have already started this process. The resulting information can help not only with any future international criminal law processes but also with future transitional activities and with creating an accurate historical accounting of events. In addition to investigations started by non-governmental organizations, the Prosecutor of the International Criminal Court, Karim A. A. Khan QC, has stated that he will seek to open a propio motu investigation into these events from the Pre-Trial Chamber. He has also called for action from states to refer the matter to the International Criminal Court, as that will hasten the investigation process. At time of writing, it has been reported that Lithuania and Canada may have made such a referral, although it unclear whether the formal process has been completed. These investigations by both non-governmental organizations and the International Criminal Court can help preserve evidence should there be any future prosecutions resulting from this situation. They can also speed up the trial process should those prosecutions begin, as at least some of the investigation will already be completed and accessible to the Court. Further, by collecting evidence contemporaneously, it means that evidence is less likely to be lost and is more likely to be accurate than if it was collected after the fact. All of this could result in a swifter criminal justice process once prosecutions become possible.

International criminal law is a tool that is available for providing accountability for international crimes. While these crimes can arise during armed conflicts like the current Russian invasion of Ukraine, international criminal law does not have the ability to prevent crimes from occurring. Thus, the calls for action regarding investigation and prosecution might seem premature. However, while it may be too early for international prosecutions, and it may be difficult for investigations to occur, statements like these send a strong message that the world is watching and can spur contemporaneous investigations and evidence collection, which may provide for swifter justice should the need for prosecutions arise.