I'm well aware that, when on foreign soil, you are subject to foreign laws. I guess what I found so disturbing was that he was hauled off and arrested on the suspicion of being under the influence. It doesn't sound like there was any attempt made to verify whether or not he was actually under the influence.
If it turns out that he was under the influence, I gotta wonder why neither the Captain, nor anybody on the crew attempted to do something, like convince the FO to call in sick or something. They weren't doing him, or themselves, any favors by ignoring the problem. Now the FO's career is over, and he has serious legal troubles. I bet that crew is facing some pretty serious questions from law enforcement and UAL management alike. I'd sure want to know why the crew allowed someone who was under the influence access to the airplane.