The Death of a Customary International Law

Roger Alford, over at Opinio Juris, has written an interesting blog post about customary international law. We know what creates such a law, at least pretty well:

1. The practice in question must be relatively uniform and consistent among the states.

2. States generally believe the practice is legally compelled. (Which is actually called Opinio Juris!)

3. Look to the history of various treaties and UN General Assembly resolutions.

But Alford raises the question of how we determine whether a customary intenational law is no longer a law? This is a pretty tricky question indeed. His first suggestion is that it could be superceded by a treaty. But have we ever seen this actually happen? Since when has something recognized as customary internationl law ever been superceded by a treaty? Alford recognizes that a customary international law may simply fall out of favor, but notes its exceedingly difficult to find any examples of such a development.

I would contend, actually, that it is the very nature of our international jurisprudence, that the body of customary international law can only grow, and almost never shrink.

Regardless of the Opinio Juris changing, or state practice changing on a wide scale…Shouldn’t the real question be whether it is even possible for something that has been previously recognized as customary international law to simply no longer exist as law? Wouldn’t that position mean that each time a Customary Internatinal Law is challenged in court that the court must totally re-analyze the conduct of states and the opinio juris instead of just being able to cite precedent? Wouldn’t that be hugely time consuming for courts?I kind of think the only way it could no longer be a Customary International Law, is through being superceded by a treaty provision.