I agree with Peter that the mere breach of the international law governing the use of force does not mean that all international law is useless and meaningless. But I don’t think Eric Posner’s pithy challenge to the international law academy on Ukraine can be so easily dismissed. International lawyers need, especially in this area, to provide a meaningful theory as to why international law affects state behavior, and why (as in this case) it seems to be having very little impact on Russia’s decision to use armed force in Ukraine. Contra Peter, the fact that sometimes constitutional or corporate law rules are ignored or violated doesn’t really answer the question here. When those norms are widely ignored (as with constitutional law rules in countries like China), then it is rational for actors in China to ignore those rules in most circumstances and most legal theorists would not call it “law” in any meaningful sense.
Which brings me to the Ukraine crisis. I agree with Erik Voeten that international law and institutions will be helpful in other ways. And I think Chris provides very helpful analysis of how international law can shape official state rhetoric. But the fact remains that the international law restraining the use of armed force has utterly and completely failed to constrain Russia’s actions in Ukraine. This is more than simply adhering to the legislative veto. This is a body blow to a foundational piece of the international legal system.
In academic terms, the failure of the Charter is evidence for both realists (who think international law never matters), but also for rational choice theorists like Posner, as to how international law really works. Rational choice folks think that international law works best (in fact, works at all only) when states have a rational self-interest to cooperate around certain legal norms and institutions. But where states no longer have such a rational self interest, states will depart from those legal norms. Compliance with international law for the sake of complying with international law is naive and unrealistic.
The Russia-Ukraine crisis also impacts real-world policymaking. If international law, or at least the Charter’s rule on the use of force, is very weak or non-existent as a tool for restraining state action, then policymakers should not rely on the Charter rule as meaningful protection against aggression.
A strong military or a network of alliances would probably have been a better idea. States must not overestimate the impact or force of this species of international law (as Ukraine’s new government seemed to do) when making decisions. And states like the United States should be careful incorporating this rule into its domestic legal processes, or over-privileging its role in its own domestic public debate.
I may be biased as an American, but the U.S. has about the right balance on this. It does not ignore the Charter, but it does not treat the Charter as having too much independent significance except to the extent it affects the actions of other states (especially its allies). The key thing to focus on in this crisis are the interests of the different states (and leading groups within states). State interests are driving actions here, and the Charter violation seems to be doing almost now work.
The fact that the Charter is plainly being violated will not necessarily mean that Charter proponents like France and Germany will get tough with Russia (in fact, both are going the other way by opposing sanctions or any NATO consultations). The fact that the Charter is plainly being violated will not mean China (another big Charter proponent) will do anything other than closely watch developments and urging “all sides to comply with international law” without naming any country.
International law can be, and often is, a very important tool for facilitating international and transnational cooperation. But it is not doing much to resolve to Ukraine crisis, and international lawyers need to admit that.