Last week, US Ambassador to the United Nations John Bolton claimed that the UN was demonstrating its irrelevance by adopting several resolutions calling on Israel to withdraw from the West Bank and the Golan Heights. Bolton argued that the resolutions were undermining the real progress being made in the peace process, and only served to advance one narrow position and to alienate Israel.
For a scholar of IR, this demonstrates the fundamental problem with international law: the bodies charged with interpreting and enforcing the law have little to no ability to enforce it. While the UN is most capable of passing symbolic, non-binding statements and resolutions, when it comes to actually enforcing the dictates of international law, it has few teeth. Rwanda is left to slide into genocide, Sudan continues to allow the janjaweed to rape and pillage while sitting on the UN Human Rights Commission, UN peacekeepers stand by and allow the Serb army to massacre the inhabitants of Srebrenica, and Kosovo is only defended thanks to the good graces of NATO.
However, that is not to say that international law has no purposes or power. It does. But not in the sense that domestic law does. International law much resembles a domestic society with a judiciary and legislature, but no police force. There are bodies that can create law and interpret it, but not to arrest law-breakers and punish them. The power of international law rests mostly in the phenomenon of legitimacy. States that conform to international law develop a characteristic of legitimacy that makes it more likely that other states will cooperate on other issues in the future, which can contribute to the creation of a legalistic international community.
Such a community still needs a police force. Lately, the US has filled this role (although leaving enforcement up to a posse means that the law will be enforced capriciously), but there is a growing movement towards internationalizing the enforcement mechanism, such as in the ICC. But, so long as the international community lacks a communal understanding of justice, fairness, equity, interest, security, and all the other concepts that go into a common identity and legal understanding, it is impossible to imagine states ceding their sovereignty to an international body with enforcement powers. Even the enlightened, post-modern institution that is the EU is running into problems with efforts to enforce its deficit rules on France and Germany, or attempts to cut farm subsidies (which contributed to the rejection of the EU constitution by France).
So, perhaps hegemony is a good thing for international law. While it may be true that the US is so powerful that it can pick and choose which laws to follow and when, it also must be recognized that without US power, there would be even less compliance with international law than there is now. That’s not to argue that US is fair in applying the law, or even always capable of solving every problem (as with N. Korea). But, when the US stays out, as it did in the early days of the Balkans crises or the initial stages of negotiations concerning the Iranian nuclear program, there is little hope for solving the really difficult problems. US hegemony may be the best guarantor of international law there is.