To quote the great Stafford Beer, the purpose of a thing is what it does (or, more specifically phrased, we cannot say the purpose of something is what it constantly fails to do).

The ICC was created in 2002 and has exclusively worked against targets of imperialists.

The ICJ is as old as the UN and was for the same types of activities as it's predecessors, again just bullying and jockying for power with legalese and arrests and prosecutions after winning wars. The US withdrew after they'd have been brought up for violations backing the Contras in Nicaragua, it's only used to go after those that can be bullied and denigrated by imperialists. Sometimes they're deserving but mostly it's just another tool to wage war.