I don't know of all of the national supreme laws throughout history, but I'm going to say the Articles of Confederation and Perpetual Union of all the ones I do know of.
It's better than an absolute monarchy and it's better than a federal union. I've always thought federal unions were a joke because they try to be a mishmash of a unitary state and a confederation and they always wind up being more like unitary states.
Would the Antarctic Treaty count? It does cover an entire continent. It's certainly has many economic restrictions that have kept Antartica a relatively useless continent, but on the other hand does not actively harm the non-existent natives or colonists.