The Melian Dialogue poses a question about the relevance of international law.
Thucydides probably inserted his opinion into the dialogue. He did, however, record a true event. The Athenians attacked the neutral island of Melos during the Peloponnesian War in violation of the norms of international law. The Athenian position was determined by power alone, so what relevance does law have in international affairs?
Athenians: For ourselves, we shall not trouble you with specious pretences- either of how we have a right to our empire because we overthrew the Mede, or are now attacking you because of wrong that you have done us- and make a long speech which would not be believed; and in return we hope that you, instead of thinking to influence us by saying that you did not join the Lacedaemonians, although their colonists, or that you have done us no wrong, will aim at what is feasible, holding in view the real sentiments of us both; since you know as well as we do that right, as the world goes, is only in question between equals in power, while the strong do what they can and the weak suffer what they must.
Melians: And how, pray, could it turn out as good for us to serve as for you to rule?
Athenians: Because you would have the advantage of submitting before suffering the worst, and we should gain by not destroying you.
The Melians refused to submit so the Athenians attacked the colony, killed all the men and sold the women into slavery.
The strangest thing about the dialogue is if the Athenians actually said “the strong do what they can and the weak suffer what they must.” It’s doubtful because it is so honest.
International Relations and Law are driven by power, not idealistic notions of universal justice. Yet states argue that their self-interested power serves universal justice. Somehow.
Rhetoric is “cheap” in international relations. It is cost-free and other states essentially ignore it, so that they too may use cost-free rhetoric.
If we take any game theory example, we can study the decision processes and consequences and clearly understand that rhetoric diverges from action. After or before every decision, a state engages in “cheap talk.” This does not alter the the decision or outcome – indeed, it may be completely off-topic and irrelevant. Rhetoric about international law appears to always deceive the domestic or international public for political benefit.
Law follows power. This is not the entire story. Who becomes powerful? It would appear to be democracies. Measured in raw military victories, democracies won the majority of their wars.