Breaking International Law for $500, Alex

According to this story in the Guardian by Ian Cobain and Luke Harding - well, let's have them tell you:

The British government is guilty of breaking international law if it allowed secret CIA "rendition" flights of terror suspects to land at UK airports, according to a report by American legal scholars.

Merely giving permission for the flights to refuel while en route to the Middle East to collect a prisoner would constitute a breach of the law, according to the opinion commissioned by an all-party group of MPs, which meets in parliament for the first time today.

And if they're breaking international law by helping the US, what's the US doing?