Now Henry Farrell piles on:
The argument that states will only adhere to international law when it is in their interests to do so is a highly plausible one. But without a generally convincing account of what those interests are, it is not very helpful. We don’t have such a generally convincing account, nor are likely to do anytime soon. Instead, we have a number of competing accounts (state interests flow from the structure of the international system, state interests flow from those of powerful domestic interest groups, state interests flow from the normative structures that they are embedded in etc). Each of these can plausibly be said to capture part of the truth, but none seems like a viable candidate to provide a generally applicable theory any time soon.
Sure. It could be in a state's long term interest to adhere to international law, even when not in the short term interest. But that isn't, as far as I can tell, the argument that Messrs Bertram and Quiggin are making; they are staking a moral claim that a particular vision of international law embodied in the UN charter ought to compel our compliance not because it is advantageous, but because it is right.
If we leave aside that claim, and just address whether it is in the long term strategic interest of the United States to submit itself to binding international law in order to invite reciprocity from other states, then I have to ask "Why?" Does it really actually invite a lot of reciprocity, or is that "reciprocity" enforced by the same means of enforcement we have now without the international law, i.e. the US military? Does it really make people like us a whole lot more? Is the system sustainable--would the US be willing to undertake the role of enforcer in exchange for a measly single vote on the security council, or will the system break down, either because the US withdraws at a bad moment, or because the US decides that it doesn't need such a big military any more? What will wannabe great powers that don't see a long-term strategic interest in international law do if this happens? Is it even remotely politically plausible that America, or any unipolar power, will consent to hamstring itself this way? Can America even credibly commit to international law provided that it is the main enforcer of same?
I realize that I'm not exactly the first genius to ask these questions. But as Henry well knows, I'm generally pretty skeptical of the ease with which these kinds of institutions can be built. The EU has worked, to some extent, but it's taken 50 years, and in the past decade has repeatedly failed to advance integration against the short term interests of powerful national constituencies. And given what the membership of the UN looks like, I'm pretty sceptical that it even should be built. Are we really going to let Zimbabwe, Sudan and Libya vote on our foreign policy?