Andrew’s reply makes a good point. I share his skepticism about my proffered explanation for the choice of hard law over soft law. The problem is that we have an empirical puzzle that demands explanation, and we lack a good one. If there is a better explanation than the one I put forward, I have not yet seen it.
The puzzle is that under Andrew’s theory we ought to see lots of soft law agreements. To some degree we do, and there is a selection bias problem to boot: soft law agreements are not always listed in the usual treaty databases, and thus it is hard to know how many there are. However, it seems hard to argue that there are more multilateral soft law agreements than hard law agreements. And it is clearly the case that major multilateral negotiations more frequently result in a hard law agreement, and when they do not they are usually viewed as failures.
The landmines issue is a good example. Spurred on by NGOs, landmines regulation advocates convinced many governments to negotiate a major agreement. That agreement resulted not in a soft law accord but a treaty. We observe this pattern again and again. Some big UN meetings do yield soft law accords (e.g., the Rio Declaration of 1992) but again, advocates in the area generally deride these as weak and vacuous. So I think the puzzle remains: why so few soft law accords? As I noted in my first post, we see many soft law accords in technocratic areas that are not politically salient, such as banking. That is consistent at least with the theory that domestic/civil society preferences might be playing some role in the choice between the two. But it is certainly plausible that other factors are at play, or that I am entirely wrong about this.
Let me briefly comment on something else Andrew said. He wrote that international law is perhaps just as oxymoronic as soft law, in that the former lacks coercive enforcement of the sort we see in the domestic context. Yet it is interesting to note that in constitutional law we don’t see very much coercive enforcement either. When President Truman lost in Youngstown, what forced him to comply with the ruling? It certainly wasn’t that the military threatened to lock Truman up if he failed to follow the Supreme Court.
We could multiply the instances easily; anytime a federal court orders a government agency to do X or not do Y, why does the executive branch follow the court and obey the law? Again, it cannot be coercive power that explains it, since the executive wields the coercive power. The point here is that the difference between international law and domestic law is not always very great, and in fact may be illusory in some instances—instances that are at the core of our domestic legal system. It is worth bearing this in mind as we think about how international law works.