The idea of trying Putin for war crimes is “trending” in social media, and some politicians like Joe Biden, German President Frank-Walter Steinmeier  and even some professors of international law are already concocting possible scenarios.
Without a doubt, the Russian invasion of Ukraine on 24 February 2022 entailed the crime of aggression for purposes of article 5 of the ICC statute and the 2010 Kampala definition of aggression. It would also fall within the scope of article 6(a) of the Nuremberg statute that defined the crime against peace.
The International Criminal Court in The Hague has, of course, a problem of jurisdiction, since neither Russia nor Ukraine are parties to the Statute of Rome of 1998.
What should the answer of the international community be to the war crimes already committed – on both sides – during this war? Both Russia and Ukraine are states parties to the Four Geneva Red Cross Conventions of 1949 and the 1977 Additional Protocols, which oblige them to investigate and prosecute members of their armed forces who are suspected of having committed grave breaches of international humanitarian law.
This raises an additional issue concerning ICC jurisdiction. Indeed, to the extent that the State whose soldiers have committed war crimes undertakes to investigate and prosecute, the principle of complementarity excludes the admissibility of those cases by the ICC. Article 17 of the Rome Statute stipulates in part:
“the Court shall determine that a case is inadmissible where: (a) The case is being investigated or prosecuted by a State which has jurisdiction over it, unless the State is unwilling or unable genuinely to carry out the investigation or prosecution; (b) The case has been investigated by a State which has jurisdiction over it and the State has decided not to prosecute the person concerned, unless the decision resulted from the unwillingness or inability of the State genuinely to prosecute.”
Accordingly, to the extent that the Russian and Ukrainian authorities carry out investigations in good faith and prosecute those responsible for the alleged crimes, the ICC is out of a job.
Could the United Nations establish an ad hoc tribunal similar to the International Criminal Tribunal for the former Yugoslavia or the International Criminal Tribunal for Rwanda? The ICTY was established by UN Security Council Resolution 827 of 25 May 1993. The ICTR was established by UN Security Council Resolution 955 of 8 November 1994. By contrast, the UN Security Council would not be able to establish an ad hoc tribunal to try Putin, because both Russia and China would certainly exercise the veto power against it.
Thus, the frequent references to the Nuremberg Trials are mostly propagandistic. The historical conditions are not given in the context of the Ukraine war. Indeed, the 1945 International Military Tribunal was only possible because of Germany’s unconditional surrender. There is zero chance of an unconditional surrender by Russia in the Ukraine war, and if NATO were to escalate further, we would be risking World War III and the Apocalypse of humanity. So, forget any victor’s justice and vae victis, because there will only be vanquished.
Of course, the progressive development of international law has led to the expansion of the concept of universal jurisdiction, which enables any country to detain a person found within its territorial jurisdiction, if that person is suspected of having committed war crimes. Some countries like Germany and Sweden have already exercised universal jurisdiction over war crimes. Especially in cases of alleged genocide, a trial under universal jurisdiction would be conceivable if a given country can establish in personam jurisdiction against persons who are deemed to be “hostes humani generis” – enemies of all mankind. Yet another possibility would be to hold a trial in absentia, which would serve the purpose of documenting the crimes, even if the enforcement of the tribunal’s judgment would be doubtful.
Those who are advocating a trial against Putin are in a typical liberal quandary – confronted by the binary scenario of clear criminality on one side and profound geopolitical hypocrisy on the other side. Professor Richard Falk writes wisely  that Nuremberg did not establish a desirable legal precedent, because the drafters of the Nuremberg statute themselves betrayed fundamental principles of legality by applying criminal law selectively, since they overlooked their own criminality, having made no disposition to investigate the dropping of atom bombs on Hiroshima and Nagasaki”, that together cost perhaps 250,000 civilian deaths (plus an additional hundred thousand for cancers, leukemia and other medical sequels) or the carpet bombing of population centres in Germany, which resulted in some 600,000 charred corpses, e.g. in Dresden, Dortmund, Cologne, Berlin, Hamburg, Kassel — attacks that had little or no military significance and could only be described as pure terror. Falk is “far from sure about what is better from the perspective of either developing a global rule of law or inducing respect for the restraints of law. The essence of law is to treat equals equally, but world order is not so constituted. As suggested, there is ‘victors’ justice’ imposing accountability on the defeated leadership but complete non-accountability for the crimes of the geopolitical winners.”
John LaForge , co-director of Nukewatch, a peace and environmental justice group, proposes in his piece “Get in Line Investigate US Atrocities First” that a compilation of NATO crimes would be in order, including wars of aggression or occupation, the bombing of hospitals and schools, the desecration of corpses, attacks on civilians and civilian infrastructures, torturing and executing prisoners of war, using banned cluster bombs, etc. “But unlike todays’ wall-to-wall news coverage of Russia’s onslaught, the U.S. media mostly withdrew from reporting on U.S. military occupations and still chooses not to present many photos or film of alleged U.S. crimes. Like news censorship inside Russia, our media’s blind eye helps maintain U.S. public support for its wars-of-choice, so protests have been raised mostly by victims, survivors, human rights groups, anti-war coalitions, and international law advocates.” LaForge’s article lists some 200 atrocities for which the US would be criminally responsible.
Personally, I would advocate convening a “Peoples’ Tribunals” with broad jurisdiction to investigate war crimes committed by all parties to the conflict. Surely the Ukrainians are compiling evidence of Russian crimes, as the Russians are compiling evidence of war crimes by Ukrainians and foreign mercenaries.
Admittedly Peoples’ Tribunals have no international recognition and their judgments are not enforceable, but they do have the added value of drawing attention to war crimes that the mainstream media has ignored or even white-washed. A Peoples’ Tribunal would also collect the evidence, listen to the testimony of hundreds of victims and identify the provisions of the Geneva Conventions that have been violated.
I can refer to the Kuala Lumpur War Crimes Tribunal that sat in 2009-11 and convicted both George W. Bush and Tony Blair of war crimes and crimes against humanity for the invasion of Iraq in 2003, which the then UN Secretary General Kofi Annan correctly described as an “illegal war”. The Kuala Lumpur Tribunal sat again in 2013 to examine allegations of genocide perpetrated by Israel against the Palestinians, and issued a judgment confirming the commission of the crime of genocide under the 1948 Genocide Convention.
The Fondazione Lelio Basso established the famous Permanent Peoples Tribunal, which has held 49 sessions and heard many cases since 1979, starting with the crimes committed by Morocco against the people of Western Sahara.
Maybe a trial of Vladimir Putin, Volodymyr Zelinsky, Joe Biden, Jens Stoltenberg and others would clarify many outstanding legal and moral issues surrounding the war in Ukraine.