Substantive Sources of the Norms
Nations as Sources
The legitimacy of the norms comes from the acts of nations. A nation can contribute to the set, much as, in domestic law, a member of a national legislature can with respect to a law or proposed law of a nation. A nation’s authority to so contribute to the norms depends not on the nation’s degree of national or individual freedom, age, system of self-governance, system of internal economics, or internal sociological structure but on it being a nation. Those other factors may have secondary effects, such as on content, and the norms generally reflect the interests of the separate nations, perhaps weighted by relative national power, but they are not the primary source of the authority. Even a purported decision by the nationals of one nation acting alone cannot adopt a norm or amend or repeal a norm. At most, the nationals can only create or terminate the nation itself, which, if existing, then can only try to adopt a norm or amend or repeal a norm with the consent of enough other nations, not an easy task for one nation alone.
Probably the stronger cases in which a nation could act unilaterally are those in which the issue is minor, meaning ‘known of but not objected to by any other nation at the time’, or the case of a more-powerful nation doing so regarding its neighboring less-powerful nations (i.e., within its sphere of influence). An example of a unilateralism is of U.S. President Monroe’s Monroe Doctrine, by which European powers were publicly told to refrain from interfering in the western hemisphere;23 this was in the U.S.’s sphere of influence and, apparently, it was more or less followed.24 Other unilateralist cases in several regions of the world in the 20th century and since may involve the People’s Republic of China, India, and the Soviet Union or Russia. A nation’s attempt at unilateral promulgation may even be at great expense but still fail; Japan in wanted the U.S. to stay out of eastern Asia and, to signal its preference, Japan attacked Pearl Harbor. If that hadn’t been a bite more than Japan could chew, east Asia might be politically very different today, with fewer allies for the U.S. and Japan politically more dominant over neighboring territory.
Overall, however, the pattern is of multiplicity of nations having similar views generating enforceable coincidences or agreements in principle about what the norms should permit and require.
On substantive content, the relevance of the norms to facts is likelier when the topic is internationally important especially to heads of state, irrelevance is perceived as costlier than relevance, and testing or assessment of facts by competing parties without resort to a scale of war that is noticed by an enemy is relatively easier.