Formal Sources of the Norms
Known Formal Sources
Norms generally are determined from opinio juris, consisting mainly of the statements of high court judges, speakers of law such as professors, and heads of state regarding what they are inclined to enforce or not; and they generally are also determined from the practice of nations. The norms are not formed directly by treaties, although a treaty may influence them, in that a provision of a treaty can evolve into becoming a norm among nations not party to the treaty, even without a whole treaty becoming a norm (and most whole treaties don’t). Proof of nations’ practice in support of a principle being a norm can even include notes by nations’ representatives in conferences and negotiations.
Speakers are not always obviously identifiable. What likely happens is that someone who may be obscure acts like a speaker, then that person gains credibility for that role, and then some authorities may accept her or him as a new speaker, probably through criteria that likely promote consistency of views on the norms from those of pre-existing speakers to those of new ones and therefore stability of the norms, and that acceptance is probably reversible at any time.
Soft law in international law is not immediately binding, but it strongly encourages authorities to make its content binding. It has a parallel in U.S. domestic law in persuasive case law, treatises, journal articles, leading forms books, and the like, many being binding on some people and more being potentially persuasive of other people. A law journal article, whether binding or not, may persuade many courts and attorneys. An appellate court ruling on a point of law, the first such ruling in the nation, may bind only one party thereto and the courts directly below on the case but persuade (without binding) most courts, attorneys, and clients across the nation. (This essay treats a legal provision as law only if and insofar as it is binding.)
Speculation on Domestic Law as a Possible Source
A norm arising directly from domestic law seems extraordinarily unlikely but possible. Consider, as an example, that, reportedly, virtually every society, even almost any small one, criminalizes murder and rape.25 So, if two groups of people create two new nations, everyone in the new nations renounces all other nationalities, neither nation has promulgated domestic law saying anything about murder or rape, in one of the new nations someone murders or rapes someone else by a definition of murder or rape that is common to most nations proscribing either act, and the murder or rape implicates the other nation such as if it was a murder or rape of a tourist from the other nation, then perhaps the other new nation is permitted by the norms to wage war against the first to punish the murderer or rapist and to punish the lack of a legal proscription of murder or rape. If that would be permitted, then clearly one way the first nation could preclude or remove a ground for war against itself by the norms (the duty of preclusion or removal is discussed infra) would be by criminalizing murder and rape because most nations do (even by sufficiently common subnational law, as in the U.S. where those are usually prosecuted as topics of State, not Federal, law, thus usually as violations of subnational domestic law, although Federal domestic law exists on point), and can domestically criminalize even without a war underway or being threatened, even by a unilateral domestic law imposed by fiat by the first nation’s head of state contrary to all pre-existing domestic law (e.g., the procedural law on enacting new law).
A narrower case is one where one nation considers an act a crime but one of lesser importance than most nations assign to it, such as if one nation treats tax evasion as a misdemeanor while most nations treat it as a felony and the one nation receives money resulting from tax evasion in other nations but refuses to cooperate with the other nations’ attempts to restrain the evasion and resulting money transfers. If the one nation being an outlier in treating the evasion as a misdemeanor is thus violating the norms, that would be a ground for war, although I don’t think it is a violation.
Thus, the only question is whether nearly-worldwide commonality of domestic law with nothing higher is sufficient for a norm to the same effect to come into being and, if so, whether that domestic law can be subnational and still suffice to contribute to the cause for the creation of a norm.
On the other hand, there is compelling reason not to let norms develop from no more basis than that most societies have certain domestic laws in common. Establishing a norm would make a domestic exception difficult or impossible and in need of prior international approval (comparable to the action of the U.S. Constitutional principle of pre-emption under the Commerce Clause restraining subnational deviation), thus rendering exceptions unavailable on one nation’s initiative and slowing or preventing international development that changes in facts might necessitate. For a nation to be able to innovate in domestic law, or to be contrary to almost all nations on some matter in domestic law, that nation must have some amount of a sovereign right to do within itself what it chooses.
While most innovations and contrarinesses fail, those proportionately few that succeed are, on average, worth more than the cost of the failures and the world society tends to become more capable and more powerful as a result. For example, it can support a larger world population through more efficient production of resources for human survival. We generally don’t want to discourage innovation that advances survival. So, a norm arising from domestic law alone, although good for stasis, is not only unlikely, it would usually be counterproductive.
Keeping norms from being shaped by domestic law except in exceptional cases may even be necessitated by the norms. For instance, a nation should not be an economic burden on other nations if it can meet its own needs, lest that burden be met by violating another nation’s sovereignty, thus increasing war. If how to meet its own needs is not obvious, in the absence of innovation from anywhere or assistance from another nation it may fall back onto some method that likely works but that violates another nation’s sovereignty, such as theft of foreign food, and that might lead to punitive war or to the punitive forcing of an alliance to make the burdensome nation wage war against some other nation on its new ally’s behalf, in either case increasing war, when the norms favor peace.
To prevent this untoward result, a nation should attempt to meet its own needs even when that would depend on innovation. Therefore, the norms have to permit innovation by nations, even innovations that likely will fail. Therefore, the norms normally have to be constrained from being developed from domestic law alone, especially from subnational domestic law alone.