History of the Norms
The First Humans
The first genetic humans numbered at least 10,000, not just two (not just the so-called Adam and Eve or the mitochondrial mother and the mitochondrial father), probably because evolution responded to opportunities and constraints so that approximately 10,000 primate lineages evolved into the earliest human species at about the same time, a minimum of 10,000 first humans being needed to support the amount of genetic diversity now found among modern humans and that number might not be large enough to account for prematurity losses due to being prey for food for predatory animals, diseases, and war. Most of the individuals in the 20,000 or so would have been proximate to each other and would, of necessity, have interacted with each other. By the time the first humans matured, a human world community necessarily came into existence; and there is no reason to doubt its continuity to today.
If only to promote self-survival, such a community would have experienced some amount of internal influence among its members. From that intracommunal influence, even if no consensus arose (and that’s unlikely), at least expectations arose (as in, hypothetically, “you move or I bonk your head”, “no, you”, thereby expressing each member’s expectation about the other). Expectation being violated implies dispute and the possibility of enforcement. Enforcement occurred at some time. From an expectation with enforcement, even if gentle as long as it was perceived as successful and precedential, law developed.
Gradually, some humans parted into separate communities that had intercommunal contact but only rarely. Those may have been the first proto-nations or nations. That term, nations, is used herein without necessarily meaning ‘indigenous peoples as distinct from later colonizers’, since the ancestry of both the indigenous peoples and the colonizers is ultimately just as old, but as meaning the ‘earliest nations that ever existed regardless of relationships of later nations with the earliest ones’. Sooner or later, the first nations, possibly the first two nations ever to exist, would have found utility in having some kind of law govern international relations, enough to abandon lawlessness. International law may have developed before there were two nations, because it could have developed when there was one nation and a thought of a second nation. It’s even possible that humans were never lawless, just, sometimes and in some places, relatively so.
Earliest Legal Imperatives
If the first nations had disagreed with each other and domestic law had developed but international law had not yet been invented, a nation could, apparently, lawfully have had its domestic law govern the world, so that every nation could, contrary to each other, have ruled the world; or, at least, they could have tried. One way is that a nation could have promulgated a domestic law outlawing resistance by an enemy nation. Surely, the proposal would have been popular at home and would have been approved almost unanimously. It likely would have been ignored by enemies but then the nation could have sued or prosecuted the enemy nationals wherever found for failure to surrender their nation or help achieve their nation’s surrender. Anyone convicted of a crime under domestic law and still under domestic sentence might have been lawfully denied postwar repatriation. Even if this was tried, it seems no such law exists today and thus no one with legal power now believes such a law could work as intended.
More subtly, a nation, by domestic law, could have contradicted some less-obvious rights of other nations and then waged war for failure to comply with the contradicting nation’s domestic law. No topic would have been out of reach. If that were a workable legal strategy, all other nations could have lost all of their rights without notice until it was too late to protest or correct it and all nations would have been able to do this to each other, resulting on first glance in each nation having no rights while simultaneously enjoying infinite rights.
This is logically impossible and, in practical terms, would lead to a deadly mess. An attempt to do this might have been lawful back then, if no law was explicitly against it, but simultaneously executing all such laws would likely have caused the death of major percentages of the human population and fear, defensiveness, and chaos in much of what was left.
Not all wars need have been due to contradiction between nations’ domestic laws. Unlimited, arbitrary, or whimsical causes also could have flared up into full-scale wars. All of these could sometimes have been too expensive for the potential gain, and, with retaliation, sometimes mutually too expensive. That would have intermittently encouraged constraint, sometimes unilaterally, even in the presence of underlying disagreement, leading to a tendency to agree to disagree at least on some trivial issues, i.e., generally to leave each other alone. That might have been good enough until a violation required amendment or enforcement. Then, if enforcement was preferred, establishing a single international legal regime for all people would have been an imperative as a constraint on war and war’s causes. If the regime was envisioned then as temporary, such as for a social experiment, the reasons for its initial creation would have commended its permanence. The existence of such a regime, once permanent, could explain there being legal norms now.
As the new international law proved beneficial for one use among one set of nations, a tendency would have been to expand the law to more uses and more nations until all currently-existing nations were by definition covered, including a nation that didn’t agree to it but which sees that its contrary position is overwhelmed by a war threat, thus giving rise to separation of norms from treaties as a separate body of law.
Perhaps hostility, hatred, or other negativity motivated splits between what became nations; perhaps economic advantage that would result from one community being made smaller and people thence considered as relatively excess by that community being encouraged to leave and form a new community to exploit a new economic opportunity in amicable mutual interest (as far as I know, no human has been sent into outer space because Earthlings preferred that he get out of their sight) meant that a division into nations could have been a positive experience. Therefore, whether xenophobia underpinned the spinning off into nations is unknown.
Later, when agriculture developed, perhaps eight thousand years ago, a reasonable guess is that conflicts, perhaps wars, between people who depended on raising food at one location and preventing other people from taking the food they raised, thus wasting the farmers’ efforts, and the people who depended on nature as they had for millions of years to supply them with food for the taking, thus permitting and encouraging nomadic travel, including through lands claimed as if owned by the farmers, may have been international insofar as the farmers and the nomads constituted separate nations within the concept of nationhood as understood in that era. What the relevant norms would have been is unclear; the norms may have evolved from favoring views of the nomads to being split between nomads and farmers to favoring views of the farmers. With such evolution may have arisen a view of a nation as generally having a fixed location and fixed boundaries, but there may have been nothing in the norms that would have always prevented fixity in nations’ locations and boundaries; it may be theooretically possible for a nation to come into being today even without that fixity, exept that if nationhood depends on recognition by at least one nation then the recognizing nation would have to accept nonfixity for the nation it recognizes.
Without attempting to sketch the century-by-century development of the norms, on which more qualified authors likely have written, worth noting is that if the number of nations has increased over recent millennia and centuries and if international contact has become more common and more sophisticated, the reach, influence, and content of the norms may have increased as well. This likely would have improved international predictability and stability, reinforcing the desire for norms.
For purposes of this essay, it’s assumed that the norms have evolved insignificantly little in the 20th and 21st centuries except for the law on nuclear weapons, aviation law, outer space law, and any topic of law dependent on new technology (it’s unlikely that anything unique to the Internet is yet in the norms, although someday something may be) and except to accommodate new understandings of physical natural law (cf., relativity was first articulated only in the 20th century and it probably wouldn’t have affected human law until then).