On this bloggingheads, Robert Kagan makes the following argument against the effectiveness of international law for solving geo-political and geo-strategic problems: i) Law qua law requires that all parties be treated equally; ii) no nation ever has, nor ever will, treat all parties equally; iii) hence, no legal framework will be applicable to inter-state relations. Of course, I don't think we'd accept this argument at all if it were made on behalf of domestic law: i) Law qua law requires that all citizens be treated equally; ii) as a matter of fact, citizens are not treated equally (richer citizens afford better lawyers, more affluent citizens can affect the legislative process to their advantage more readily, many minorities are at a distinct disadvantage in lobbying for access to public goods and influence, etc.); iii) hence, no legal framework at all will be applicable to intra-state relations.
But I'm not going to make that point. Regardless of the argument's strength, isn't the first premise obviously false? I mean, before the age of Enlightenment, the idea that the laws must treat all individuals equally was, I'm pretty sure, non-existent. In fact, quite the opposite was true: a primary function of laws was to codify, legitimate and enforce the inequalities among parties by virtue of lineage, wealth, status, occupation, etc. And while very few regimes were what I would call admirably just, quite a lot of them were functional and did manage to advance their interests and values through a legal framework, both internally and externally. If I were forced to pin Kagan's basic mistake, it would be the assumption that law has to be naive and/or ignorant of real relations in order to function as law. In some cases, yes, but not all. Per the issue at hand in the bloggingheads, I see no reason legally why the Nuclear Club members can't just insist that they're better, they should have more say in shaping world nuclear policy, and then construct international law to reflect this (which, of course, is exactly what we do!). Now, there are good arguments for why this is an unjust arrangement, but that's not the issue: the issue is whether it's effective.