they seek a declaration from the court that defendants are violating their duty under customary international law
Here’s the nasty little secret about “international law” that people don’t seem to understand. The most powerful countries don’t have to abide by it. There are no mechanisms for enforcement. There aren’t world police who have international jurisdiction, there aren’t world courts that have international subpoena power. So the countries at the top can enforce it when it’s in their interest, and ignore it when it’s not. Them the rules of an anarchical system, “rules for thee not for me”