In the seventeenth and eighteenth centuries the antiquarian interests of the Humanists gave place to the new rationalism of the school of natural law. Believing that the law for any society could by the use of reason be derived from principles inherent in the nature of man and society, the adherents of this school rejected the unquestioned authority which the medieval Commentators had accorded to the Corpus Iuris, and yet found in the Roman law, with its doctrine of the ius gentium and the ius naturale, a great deal which they could accept as being the embodiment of natural reason.
The first of the great exponents of the new doctrine was the Dutchman Grotius (Hugo de Groot, 1583-1645), who applied it especially to the formation of a body of international law. It was indeed in this field that the school of natural law was most influential, but it encouraged also the elimination from the modern Roman law of the irrational, and therefore peculiarly Roman, features which the Humanists had emphasized, and insisted, even to excess, on the place of logic in law. (Thomas, 1976) Natural law ideas led also to a call for codification.
The ideal of a logically consistent set of principles and rules could best be realized and preserved in a written code. The call was partially answered in Bavaria (1756) and Prussia (1794), but incomparably the most important event in the history of modern European law was the enactment of Napoleon's Code Civil in 1804. (Kunkel, 1966) Its importance lay not so much in the fact that France, for the first time in her history, had a single system of law, as in the fact that the Code was adopted or copied by many other countries.
Sometimes its adoption was the result of conquest by Napoleon, but its attraction continued long after his final defeat and is attributable partly to the clarity and simplicity of the Code itself, and partly to the prestige of France in the nineteenth century. Codes more or less closely copying the French were adopted in Holland, Spain, Italy, Belgium, Louisiana, Quebec, Egypt, and in many parts of South America. (Schulz, 1951) In Germany, too, a French code might have been adopted at the end of the Napoleonic wars but for the influence of the great jurist Savigny (1779-1861).
He argued that the time was not yet ripe: a far more profound study of the Roman law than had been achieved by the medieval lawyers or the school of natural law was necessary before a satisfactory code could be achieved. Thus began the last great period of the practical application of Roman law. In the hands of Savigny and his successors the Corpus Iuris was made to yield a highly systematic, closely analyzed, and remarkably elaborate body of law (Pandektenrecht) for nineteenth-century Germany.
It was not until the establishment of the German Empire that, on the foundations thus laid, the work of codification was begun, and not until 1900 that the German Civil Code finally came into force. More systematic and more elaborate than the French, it too has been copied elsewhere, by Japan and Brazil, for example, and its influence can be seen in the Swiss Code, which in its turn has been adopted by Turkey.
The movement for codification brought the second life of Roman law in one sense to an end. Except in South Africa and Sri Lanka, where the pre-Napoleonic Roman-Dutch law survives, the Corpus Iuris has ceased to be a direct source of law. Nowhere else can it be cited as authoritative, except on occasion where a code is silent or ambiguous? And yet in another sense codification gave Roman law a new life and extended it to territories into which it could never otherwise have entered.
Uncodified systems are unsuitable for export, and by modern standards the Roman law is an uncodified system. The uncodified Common law has indeed spread over the globe, but it has followed the flag. It has only taken root where British rule, and with it lawyers trained in the Common law, have gone. Codes, on the other hand, as we have just seen, travel easily. But we must beware of exaggerating the extent to which the modern codes embody Roman law.