International Law is elusive...mostly without a tangible solution or rule

Well, that's how all law is interpreted, but it is different from nation-state-based law, though I think the International Court has helped to further the stature of international law in terms of the law of many nations, not merely bi-lateral / small numbers of nations in highly specific treaties.

No. It's well understood. It's encoded in the results of the Nuremberg trials, the UN charter and the Geneva Convention, for example.
Conservatives hate peace and regard international law as a speed bump in their path to conflagration.

International law is only as strong as the participants' adherence to it. Unfortunately it is widely ignored when inconvenient to individual countries, particularly powerful ones, and nobody can do anything about it. So it's impotent when it really matters.