Breaking the Law to Change It?

"Yet that doesn’t mean international law would view a U.S. intervention as illegal in the long run." This seems to be the strongest case on international law grounds, but given the questionable value of military action, I question it being used in this context. This debate also has led to those "what is so special about torture" sort of things. If a law professor, per a reply to me, is so clueless, maybe the general public needs a thumbnail reminder?