Blackstone
Brigadier
History is very important, it shows great powers can break all sort of international rules and get away with it. I don't mean little inconsequential ones, I mean breaking the ultimate Westphalian rule of invading other sovereign states.I already said that flouting rules is always an option but it also comes at a cost. The discussion isn't about history and so I am not sure what is frankly your contention.
Here's a prediction if the ICJ rules for Philippines and China laughs it off: NOTHING consequential will happen. There will be no military actions against China. There will be no sanctions against China. There will be no embargo against China. There will be finger wiggling; there will be foot stamping. Senator John McCain will surely call for bombing of Beijing, but he will be dismissed for being himself. President Obama might cancel some worthless inter-governmental conference or some other nonsense, and Secretary Carter will ape some incomprehensible diatribe. There may even be a useless UN Security Council draft to condemn China; which will be vetoed by not one, but two permanent Security Council members. But that's about it.
It ends with China keeps on trucking, ICJ loses credibility, the world finds a way to accommodate, Philippines elects a new President who will then go to Beijing with hat in hand, and everyone continues to fight for spots on the "One Belt, One Road." Life goes on.