(Also, like Posner, I wonder if you appreciate how radical your argument really is. According to you the US and Britain did nothing wrong whatsoever in going to war without UN approval, they just made what was at best a tactical error. Many people around the world would strongly disagree with that.)

Using a term like “institution” is bound to create misunderstandings when discussing international law, because I took it as you referring to those actual established official organizations, like the U.N., the ICJ, etc. And looking at that level, you are bound to see many differences and very little in the way of unifying conception.

However, if we are both looking at it at the higher level of the rules, customs, and traditions governing states, I don’t see why it is so hard to see that the unifying concept there is that these are institutions that cannot be enforced by a third party that is above all others. In a very real way, states only accede to third parties that are above them in some way via consent of the governed, by treaty. And this is a very recent phenomena in international law, less than a century old. Otherwise, every other state is on the same level as every other state, and that introduces different strategies and institutions for making behavior predictable.

As for your disagreement with me, that institutions may have other effects beyond controlling behavior, I would demur merely by saying that the aim of international law is to make the conduct of other people predictable, and controlling behavior is but one way to do that. Coordination is another way, and there are other effects that can contribute to that aim. We do not disagree on this point at all.

And here, the Goldstone report was exactly right – the ‘but he did it first’ excuse is not, and cannot be a justification for committing war crimes.

While at some level this is correct, I think you need to examine the law of war carefully before you apply it too broadly. There are a number of things that are quite legal under the codified law of war (the “Geneva Conventions”, although in this case that’s shorthand for a larger body of treaties and some conventional practices) that would be war crimes absent the actions of the opposed state. Reprisals come immediately to mind, as does destruction of facilities marked as medical. As a more specific example, perhaps not irrelevant to the campaign under discussion, a combatant sheltering among non-combatants is not only probably committing a war crime himself, but causes it to be legal to cause casualties among those non-combatants (a simplification of the reality—the non-combatants don’t lose all protection—but one that is true in essence, at least as I understand the situation).

Moving from the statement of what the law is to why it’s that way, it may be that things like reprisals are the “enforcement arm” of the law of war. There aren’t many ways to enforce international law in general or the law of war in particular, but recognizing that breaking the law of war will bring harm to you seems an approach to that.

None of the comments above should be taken to say that it’s wise to take such actions, or that I’m expressing an opinion on either the legality or wisdom of either side’s actions in this campaign.

International law, as Gandhi said of Western civilization, is a good idea.

I think this, while not totally wrong, shows a confused approach here, one that’s apiece with some of the general confusion you discuss. This way of thinking about WTO law seems to want to assimilate it to criminal law, but it’s not like that- it’s much more like contract law. The retaliation measures are not best thought of as “punishment” but as self-help measures, like the sort that one can take in contract law if the opposing party doesn’t comply with a judgment- attachment, garnishment, etc. They are not completely comparable, but more similar than criminal punishment. And, compliance with private law decisions in domestic courts is not significantly better than is compliance with WTO dispute body resolutions. Finally, Posner’s way of thinking of the issue here seems to me to over-state the extent that fear of punishment, rather than desire to follow accepted norms, plays in law. So, even in extreme cases like the dispute between the US and Antigua over internet gambling, where Antigua would certainly hurt itself vastly more than it would hurt the US (and might barely hurt the US at all) if it were to actually impose the retalitory tariffs authorized by the appellate body, and so likely won’t impose them, the US is slowly working on coming into compliance (slowly, for sure, but it does seem to be happening.) This seems to be because of a desire to make the system work and not be seen as a bad actor. (Because of internal division this is hard, but is still mostly accepted, I think.) But this is how really large portions of domestic law works, too- if people only obeyed because of fear of punishment we’d have a vastly different and much more unpleasant world.

None of this is to say that international law, in any of its aspects, is just like domestic law. It’s not, and assuming it is is also a big mistake. (Much of international law is parasitic on domestic law, for example, in a way that domestic law isn’t parasitic on something else.) This is also not to say that many international law boosters don’t make strongly over-stated claims, perhaps especially about international “common law.” (Most times I hear someone talking about an “emerging consensus” that grounds some bit of international common law I expect a lot of fluffy thinking to follow.) But it seems to me pretty clear that Posner can only support his stronger claims at all if he basically ignores international economic law, but doing that is to beg the question pretty substantially.

Yes, especially in trade and commerce regulation, where international law and agreements can help make an endrun around vested interests nationally, as well as provide governments with cover for unpopular decisions. Succesive neoliberal governments in Europe and America have used the WTO/GATT/GATS structure, as well as the EU as a way to force “liberalisation”and privetisation on their voters, making these adjustments not just unavoidable but unrepealable.

Henry, replace “international law” with “political science” or “economics” or “philosophy” and I think see why I think this sentence is almost as wrong-headed as what Bernstein spouts. Your position, that international law bundles together a bunch of institutions, is mistaken because it looks at it from the level of institutions, not from the higher level that you begin to elicit in your last paragraph.

If you think that law is the command of the legislature, compulsory jurisdiction of the judiciary, and the decree of a popularly elected executive, you’ll be depressed about anything concerning international law. But if you understand that law is about regulating behavior, you understand that mandating certain behavior is not the only way to control behavior. Agreements (i.e. treaties) and custom can be as effective in controlling behavior as law handed down from above. And this is not to say that everyone will follow international law, but everyone doesn’t follow domestic law, either, do they? The concept of law is deficient if it does not also hold the concept of lawbreaker as well.

What Exactly Does International Law Mean? It means to make the conduct of other people predictable. The same as domestic law. The means to do so differ, because international law is mainly concerned with states, but the aim is still the same.