Surprisingly, I find myself agreeing with BTS in theory here. If MD doesn't like the way CA is acting on an issue, they take it up in Congress - they don't secede.
The UN is the forum for presenting these problems and obtaining international approval and justification regarding your actions. Which is, BTW, the reason the US will be sure to have its lawyers lock in an approval before acting. [img]graemlins/thumbsup.gif[/img]
But, the problem here with the withdrawing, etc. - this is the problem with international relations generally. It's basically contract law and non-binding. Plus, it's FOREIGN contract law to Brits and Americans. Ever write a contract with a Russian? It's not nearly so clear - lots of "it is our intent to" and "we aspire to" BS-type language with little enforceability. This is even more true when dealing with middle eastern and african nations.
The UN simply has no teeth. Signing on should put you in a situation where you can't withdraw without being in breach of the UN Charter. Too bad it's not that strong.