But there is no "legal" framework for resolving this issue. There is no ruling legal authority, nobody you can sue, no judge who will decide in favor of one side or the other.

For the most part. It's not always true - countries do enter into treaties with each other, and there are international legal institutions and courts for things like trade law.

The framework in which those sorts of conflicts are resolved, and have been for centuries, is diplomatic, not legal. That means the issue is subject to treaty but also to negotiation, the general state of relations, and other squishy niceties.

And by force, by might makes right. That might be the real world we live in, but that doesn't mean I have to like it, or can't think other arrangements might be better. I would like to see a world where territorial integrity is respected, for example, and that there is some kind of internationally agreed process for holding malefactors accountable.

Not true, presumably you're going to respect e.g., the Geneva Conventions regarding your enemy POWs.

Yes, I agree with you here. I just meant that when you're at war you don't generally respect the territorial sovereignty of your enemy.

But, as you point out, other restrictions (such as how you may treat POW's) still apply.

What if a country is informally and secretly at war with you?

Don't know. You could declare war yourself, then do what you want since war essentially means you are not going to respect international laws or norms anymore in relation to your enemy. It probably doesn't much matter in practice since the gloves are already off.

What if there isn't enough of a country there to declare war on?

Then it's open season! Seriously, if authority has totally broken down, there is no sovereignty to respect, so go get the bastard (but be sure to give him or her a fair trial back home).

What if the mountain goats are hiding OBL and his bearded and one-eyed sidekicks? Whose ambassador do you slap in the face with your gloves?

As long as OBL is hiding inside the well-established borders of a sovereign nation, then you have to get their approval. If they can't get him themselves, you at least have to get their blessing to get OBL on their turf.

It is also unlawful to harbor a fugitive. Why are you arbitrarily siding with one breach of the law over another

Because of sovereignty? Is that all you got??

I'm not siding one way or another. Harboring a fugitive terrorist is not OK. But that does NOT justify violating another nation's sovereignty. By all means, take action against the offending country. Apply diplomatic pressure, negotiate terms for extradition, impose sanctions, refuse to trade, hell, even declare war if they are actively assisting terrorists to plan and carry out attacks on you. But just because a country refuses to extradite someone, this is not justification for just going in and taking the guy.

What if the result of the host country's refusal to extradite resulted in a war that caused massive civilian casualties?

What if, what if. Blah blah. What if the guy is actually innocent? How do you know he's guilty? What if you kill 20 civilians to get at him or her? We could play this game all day. If you don't like the relevant law, work to change it.

Again, I'm not saying you have to just sit on your hands and bemoan your sad fate. Take action, but take LEGAL action.

Rendition doesn't always violate the sovereignty of another nation. Sometimes it's done with the cooperation of that nation. That's the thing about not making distinctions.

I thought rendition implied a lack of consent. If consent is given, isn't that extradition instead? I know there was a discussion about this recently, so sorry for not following it if that question has been answered already.

Regardless of the proper term, if a government cooperates with a foreign power in the apprehension of a person of interest in their territory, that's fine with me. It's the notion that a foreign power can go into a country and just nab someone without consent that is a problem.

If you really believe kidnapping/renditioning is categorically unacceptable, then please explain why the US should NOT have kidnapped Himmler, Hitler, Goring, Goebbels, Hess, Borman, Speer, or Eichmann in, say, 1943, had it had the chance to do so.

In your example the US and Germany were at war. We were firebombing their cities for God's sake. It would have been fine to kidnap any of the German higher ups.

If war has not been declared, then kidnapping citizens or guests of another sovereign country is verbotten.