America is a law unto itself when it comes to signing multilateral treaties

Who makes the law of the sea as China and Vietnam clash over China moving an oil rig close to an island some 150 nautical miles from the Vietnamese mainland?

One would hope that China, which has ratified the UN Law of the Sea treaty, would seek international arbitration. It refuses to.

Has this got something to do with the fact that the US has not ratified the treaty? The Chinese don't say so explicitly, but if the world's only superpower refuses to sign up, why should China pay the treaty due regard?

As for the US itself, it has an awful track record in ratifying international treaties, usually thanks to the Senate's habitual blocking behaviour. It takes only one-third of the Senate to stymie a treaty. Even though, for example, the US played an important role in setting up the International Criminal Court for prosecuting war crimes, and president Bill Clinton wanted the US to sign up, the threat of the Senate that "it would be dead on arrival" meant it was never submitted for ratification.

Nevertheless, as is often the case with the US, it supports the court's work in day-to-day practice. It does the same with the Law of the Sea. Still, failing to ratify makes the US position rather weak when it tries to lean on China to get off Vietnam's back.

David Kaye writes in Foreign Affairs that the Senate "rejects multilateral treaties as if it were sport". After the first world war, it rejected the US joining the League of Nations, the precursor to the UN. Perhaps membership would have helped avert the rise of Nazi Germany by forging a more sensitive policy over German reparations. Who knows?

In more recent times, the US rejected the Convention on the Rights of Persons with Disabilities, the Kyoto Protocol on climate change, the Comprehensive Nuclear-Test-Ban Treaty and the Convention on the Rights of the Child (which only Somalia and South Sudan, besides the US, have not signed).