More than 74,500 war crimes have been alleged in Ukraine since Russia invaded. But bringing those to trial is no simple task, with successful prosecution requiring a high standard of proof.
The International Criminal Court's arrest warrant against Russian President Vladimir Putin on Friday is just one strand in a complex web of international and national legal moves over alleged war crimes in Ukraine.
As the world marks the one-year anniversary of Russia's full-scale invasion of Ukraine, Kyiv is seeking justice for the thousands who have been killed and wounded.