The United Nations' top court will decide on Friday whether it has jurisdiction to rule in a case brought by Ukraine over Russia's brutal 2022 invasion, with Kyiv urging reparations.
Ukraine dragged Russia before the International Court of Justice only a few days after the invasion, seeking to battle its belligerent neighbour on all fronts, legal as well as diplomatic and military.
When Russian President Vladimir Putin ordered the invasion on February 24, 2022, part of his reasoning was that pro-Russian people in eastern Ukraine had been "subjected to bullying and genocide by the Kyiv regime".
Two days into the invasion, Ukraine filed a suit at the ICJ, "emphatically denying" this and arguing that Russia's use of "genocide" as a pretext went against the 1948 UN Genocide Convention.
In a preliminary ruling in March 2022, the ICJ sided with Ukraine and ordered Russia to halt its invasion immediately.
But Russia objected to this judgement, saying the ICJ, which decides on disputes between states, had no legal right to decide in this case.
It also pressed on with its invasion, showing again the difficulty the court has in imposing its rulings, which are supposed to be legally binding on states.
At a hearing in September, Anton Korynevych, Ukraine's representative at the court, charged that "Russia's defiance is also an attack on this court's authority."
"Every missile that Russia fires at our cities, it fires in defiance of this court," he said, standing just metres from his opponents in the gilded Peace Palace where the ICJ sits.
Russia's lead representative Gennady Kuzmin countered that Ukraine's legal position was "hopelessly flawed" and "at odds with the longstanding jurisprudence" of the court.
Kyiv's case that Russia "abused" the UN Genocide Convention as a reason to launch its war against its neighbour in February 2022 "couldn't be further from the truth", said Kuzmin.
Mere "statements" about genocide are not admissible under international law including the Genocide Convention, runs Moscow's case.
Thirty-two allies of Ukraine also argued in support of Kyiv. The ICJ dismissed a bid by the United States to join the case.
The ICJ ruled Wednesday in a separate case filed by Ukraine alleging that Russia financially backed separatist rebels in eastern Ukraine for years before the invasion.
The court mainly sided with Russia, tossing out most of Ukraine's requests and saying that Moscow had only failed to investigate possible breaches of terrorism financing law.
The ICJ is under heightened scrutiny at the moment with a high-profile case about the war in Gaza.
In a judgement beamed all around the world last Friday, it ordered Israel to take all action necessary to prevent genocide during its operations in response to the October 7 Hamas attack.
