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International legal theories

Theories explaining international law

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Through International law, Coercion and Enforcement

Classical approaches to international law

International law in ancient Rome

The idea of international law in Roman times is a complicated one. For, not only does the Roman Republic and following empire itself dominate a long period of time in history, but also the very debate over whether or not the term "international law" is an applicable term is not yet decided. Many scholars and authors define international law as "the law governing relations between sovereign, territorial states." Any attempt to find a similar parallel in Roman law would find a logical starting point in the ius gentium (the laws of nations). The ius gentium began as a Roman recognition of like legal practices and institutions (such as slavery) that was found at that time in most states. This brand of law was in fact private law in itself and mainly dictated the way in which the Roman state was to deal with individual foreigners, not entire states. However, when citizenship was granted to all free men in the empire in 212 A.D. ius gentium ceased to cling to its original definition and instead was applied to states as a whole. Some semblance of modern international law can therefore be found in this shift. The actual extent of these origins and their relevance to modern law is a topic that has not yet been approached in any depth.

Natural law

Many early international legal theorists were concerned with axiomatic truths thought to be reposed in natural law. Sixteenth century natural law writer, Francisco de Vitoria, a professor of theology at the University of Salamanca, examined the questions of the just war, the Spanish authority in the Americas, and the rights of the Native American people.

Eclectic or Grotian approach

Hugo Grotius, a Dutch theologian, humanist and jurist played a key role in the development of modern international law. In his De jure Belli ac Pacis Libri Tres ("Three Books on the Law of War and Peace") of 1625, and drawing from the Bible and from St. Augustine's just war theory, he argued that nations as well as persons ought to be governed by universal principles based on morality and divine justice. Drawing, though, from domestic contract law, he argued that relations among polities ought to be governed by the law of peoples, the jus gentium, established by the consent of the community of nations on the basis of the principle of pacta sunt servanda, that is, on the basis of the observance of commitments. On his part, Christian von Wolff, contended the international community should be a world superstate (civitas maxima), having authority over the component member states. Emmerich de Vattel rejected this view and argued instead for the equality of states as articulated by 18th century natural law. In Le droit des gens, de Vattel suggested that the law of nations was composed of custom and law on the one hand, and natural law on the other.

During the seventeenth century, the basic tenets of the Grotian or eclectic school, especially the doctrines of legal equality, territorial sovereignty, and independence of states, became the fundamental principles of the European political and legal system and were enshrined in the 1648 Peace of Westphalia.

The early positivist school emphasized the importance of custom and treaties as sources of international law. Early positivist scholar Alberico Gentili used historical examples to posit that positive law (jus voluntarium) was determined by general consent. Another positivist scholar, Richard Zouche, published the first manual of international law in 1650.

Legal positivism became the dominant legal theory of 18th century and found its way into international legal philosophy. At the time, Cornelius van Bynkershoek asserted that the bases of international law were customs and treaties commonly consented to by various states. John Jacob Moser emphasized the importance of state practice in international law. Georg Friedrich von Martens published the first systematic manual on positive international law, Precis du droit des gens moderne de l'Europe. During the 19th century, positivist legal theory became even more dominant due to nationalism and the Hegelian philosophy. International commercial law became a branch of domestic law: private international law, separate from public international law. Positivism narrowed the range of international practice that might qualify as law, favouring "rationality" over "morality" and "ethics". The 1815 Congress of Vienna marked the formal recognition of the political and international legal system based on the conditions of Europe.

Modern legal positivists consider international law as a unified system of rules that emanates from the states' will. International law, as it is, is an "objective" reality that must be distinguished from law "as it should be." Classic positivism demands rigorous tests for legal validity. Extralegal arguments (i.e., arguments that have no textual, systemic or historical basis on the law) are deemed irrelevant to legal analysis. There is only hard law, no soft law. Criticisms of positivist international legal theory include its rigidity, its focus on state consent, without allowing for interpretation, and the fact that it does not allow moral judgements regarding a State's conduct as long as it follows international norms.

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