There isn’t really such thing as international law. Only treaties between states that are sovereign, and as such can tear them up if they do not wish to abide to them anymore.

"International rules and customs" would be a better term. International Law is real but it is not "law" in remotely the same way that domestic laws are and using the same word for them is confusing.

Rules, customs and precedent. Which is pretty much the basis for law anywhere.