There are two conceptions of ‘law’ that are not limited to particular nations or kingdoms. The first is what is most often known as ‘natural law.’ This is the idea that, antecedent to the laws made and promulgated by humans, there are moral laws or laws of good and evil that are evident in nature itself. In some contexts, defenders of natural laws believe that they take precedence over human proclamations of what is lawful. One of the early systematic treatments of natural law was carried out by Thomas Aquinas in the 13th century. He was not the originator of the idea of natural law, however, as one can find traces of the concept in the work of the Roman orator and philosopher Cicero as well as in Sophocles’ great play, Antigone. In this drama, Antigone confronts the king, Creon, arguing that there are laws prior, and more authoritative, than his laws or decrees. She describes a kind of law that is eternal and not subject to the course of human history: “These laws are not for now or for yesterday, they are alive forever, and no one knows when they were shown to us first.” Aristotle was an early advocate of such a view of law: “There is in nature a common principle of the just and unjust that all people in some way divine [that is, ‘divine’ as in ‘discern’] even if they have no association or commerce with each other” (Aristotle, 1991, On Rhetoric I:13:102).
In another sense of ‘international law,’ what is referred to is the presence or absence ofpractical judicial proclamations by a sovereign body backed by sanctions. In much of world history, the closest we have come to international law in this sense are political situations in which a human power, such as the Roman Empire, reaches such a high of authority that it is able to regulate and govern a large region, like the Mediterranean. In the modern era, the credibility of international law has increased insofar as there are world courts and the means to enforce laws that are promulgated. In the past, however, justice at an international scale (and thus international justice) has been enforced by individual sovereign nations. For example, Britain on February 22, 1807, declared the Atlantic slave trade abolished, and enforced the ban with its Royal Navy and marines. This was a case of international law being introduced not by a world community, but by a single power.