“While the UN Charter serves as a kind of world Constitution and article 103 is unmistakable in stipulating that the Charter prevails over all other treaties, the political narrative does not always conform to this legality. There is a degree of “fragmentation” in international law, which States invoke self-servingly to apply international law selectively, violating general principles of law — not by accident, but deliberately and calculatingly, just to see whether they can get away with it.”