Germany's foreign minister on Monday recommended that a "new format" of special international tribunal be established to "bring Russian leaders to justice." 

"Cluster bombs dropped on peaceful civilians, torture prisons in dark cellars, the abduction of thousands of Ukrainian children — nothing can justify Russia's rampage in Ukraine, which is against international law," Annalena Baerbock said.

Baerbock made the suggestion during a visit to the International Criminal Court in The Hague in the Netherlands. 

Although the ICC has sent expert teams to Ukraine to investigate possible war crimes, its jurisdiction over Russian suspects is questionable at best. 

Russia, like the US and China, has not ratified the Rome Statute that grants the ICC jurisdiction. It typically does not extradite its citizens.

Ukraine is also not a fully-fledged ICC member, although it did sign a special dispensation giving the court the right to prosecute war crimes on its territory since conflict with pro-Russian rebels originally broke out in 2014.

Baerbock said that what was needed was "a tribunal that can investigate the Russian leadership and put them on trial," during a speech at the Academy of International Law in The Hague. 

Ukrainian law as jurisdiction, with international partners? 

"We talked about working with Ukraine and our partners on the idea of setting up a special tribunal for crimes of aggression against Ukraine," Baerbock said. She said such a body could derive its jurisdiction from Ukrainian law. 

She said the tribunal could also include international elements, "at a location outside Ukraine, with financial support from partners and with international prosecutors and judges, so that impartiality and legitimacy are guaranteed." 

Baerbock said she had discussed the idea with her Ukrainian counterpart Dmytro Kuleba last week during her surprise visit to the eastern city of Kharkiv. 

She said the proposed solution was "not ideal, not even for me," but said it was necessary "because international law currently has a hole in it." 

But she offered few details how such a tribunal would be any more likely to secure Russian leaders for trial than the ICC, save for calling for the Rome Statute to be reformed so as to send a "very clear message to the Russian leadership, and by extension to all others in the world, that a war of aggression will not go unpunished in this world." 

Doubts raised by ICC's chief prosecutor

The German Foreign Ministry later published a series of posts on Twitter in German expanding on Baerbock's speech. One suggestion was to make military aggression comparable with genocide, crimes against humanity and war crimes — meaning that it would suffice for the victim state to be bound by ICC jurisdiction, not the aggressor. The potential difficulties of arrest or extradition were not explored.

ICC chief prosecutor Karim Khan, who has been leading the Hague-based court's mission in Ukraine, has warned that such plans bring risks of legal fragmentation. He argues his court would be best placed for such prosecutions, and called on member states to fix the "gaps that are said to exist" in international law. 

Meanwhile, Ukraine has tried some Russian prisoners of war in its own courts since the war began. However, the chances of catching the highest-ranking military officers, let alone Russia's political leadership, seems much more remote.

Baerbock also held talks with her counterpart from the Netherlands, Wopke Hoekstra, and was expected to speak with Prime Minister Mark Rutte.

The patchy record of the ICC and ICJ

The International Criminal Court and the International Court of Justice are the two main organs of international law at present. 

The ICC prosecutes individuals charged with severe war crimes. The ICJ is charged with resolving legal disputes between states. But both ultimately have limited power. 

The ICJ could in theory seek to prosecute a state for breaching Chapter VII of the UN Charter, which deals with "threats to the peace, breaches of the peace, and acts of aggression."

But that most likely wouldn't work in case of a political behemoth like Russia. As a permanent member of the United Nations Security Council, Russia has a veto power and could either block or simply ignore any ruling against itself, as the US did with the 1986 case where it was ordered to pay Nicaragua reparations for laying mines at Nicaraguan ports and funding militias. 

In the ICC's case, very often extradition or securing a defendant at trial is the principal hurdle to prosecution. Russia's cooperation is unlikely, particularly for higher profile defendants, even though in theory the ICC says anybody can face trial there.

The ICC has indicted and investigated heads of state in the past, including Sudan's Omar al-Bashir and Kenya's Uhuru Kenyatta. But none have been arrested and brought to trial.

The one near-exception to this came at the International Criminal Tribunal for the former Yugoslavia — the UN court set up specifically for the Yugoslav wars of the 1990s and their perpetrators. Slobodan Milosevic became the first former head of state to be indicted and tried, but he was found dead in his prison cell in 2006, five years into the case and prior to a verdict.

For the current conflict in Ukraine, "a comprehensive international justice response requires Ukraine and the international community to pursue justice through different avenues, including at the international and national level," Denis Krivosheev, Deputy Director at Amnesty International's Research center for Eastern Europe and Central Asia Region, told DW.

Baerbock seemed to concur at the Hague on Monday. 

"As long as the world order is solely based on power, only those who are strongest and use their power most ruthlessly will prevail," she said. "This means that no smaller country could sleep peacefully."

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