You're a smart, reasonable guy. What exactly is it about international law that you find interesting enough to write your dissertation on it?
As far as I'm concerned the entire thing is [...] for naive pacifists. Sovereignty and interests undermine any true enforcement. In short, it's a ruse.
Realists...telling it like it always will be.
Seriously though, I don't understand your interest.
This is a typical picture of international law, but one that I think is wrong. Two reasons for this:
1. Sovereignty is somehow excluded from the set of values international law is created to enforce. However, the first accomplishment of international law was establishing the value of sovereignty. According to the usual story (see, for example, the entry on Article 2(1) in Bruno Simma's commentary on the United Nations Charter), the development of international law tracks the development of the modern theory of state sovereignty. The idea that a state is an entity for whom the people within the state and only those people ought to have a say in their form of government and way of life is strongly opposed to a medieval conception in which the Pope, the state leader next door, or anyone with the power to do so may intervene as they like in the affairs of others.
As a consequence, sovereignty is a value enshrined in international law. In the UN Charter, for example, Articles 2(4), 2(7) and 51 are continually cited as the backbone of the current international system. For some international lawyers, sovereignty just is the general principle of international law, without which it wouldn't exist.
It is true, of course, that sovereignty allows a lot of bad things to happen. But we need to be able to distinguish two things: the current system in which sovereignty functions as primus inter pares, often to the exclusion of other principles, and one in which sovereignty is one value among many. We should not be so quick to dismiss all applications of the principle of sovereignty as 'realist.' After all, it is the claim to sovereignty and non-intervention that worked so powerfully in post-colonial states. They remain sovereignty's firmest advocates; it's the powerful states of the world who are willing to cheat on the principle.
Therefore I think it's fair to say sovereignty should be a feather in the cap of international law advocates, not its opponents.
2. On the question of enforcement: again, it depends on what one is trying to enforce. There has been a notable decline in interstate war since 1945; the place of sovereignty has made it more difficult to justify colonial adventures--not impossible, but more difficult than it should be given the relative power involved. I think the record here is mixed, but far from uniformly negative.
It does appear to be the case that at least some governments submit to international law even when it's contrary to their interests. And one should note that, however mixed the motives have been, the human rights portion of law has been progressively legalized and institutionalized. There have been plenty of opportunities for states to stop the process, and most have chosen not to. The surprising thing about the ICC, for example, is not that the US refuses to join: it's that so few other states included reservations or understandings when they did.
The larger point concerns the role of ideal and non-ideal theory. Believing the study of international law is useful does not commit one to the belief that international law is simply a organizational matter: get the institutions right and bad behavior will stop. But we should have some guiding idea, regardless of whether we think it can be implemented in whole. Otherwise it will be too difficult to tell what qualifies as progress and what as a problem in need of a solution. A picture of justice on an international scale can at least help with some big problems.
The big-picture, ideal vision is needed when it comes to smaller scale questions. As some philosophers will note (e.g. Allen Buchanan in Justice, Legitimacy and Self-Determination), political theory requires awareness of institutional context. All ideas will be put into practice by agents with imperfect knowledge and motivations. The point is not to engage in theory to create a perfect world in which no one ever fights or has reason to fight. The point is to recognize that we can judge the difference between better and worse, and work, on the margins, to make the system we have more sensible and just.