The disciples of Kant and Bentham accepted the traditional view that law consists of stable, non-instrumental rules. But they produced highly simplified versions of their masters' theories and ignored or disparaged the need to consider how such rules can accommodate the contingency of the human world. As a result, their critics found it plausible to conclude that equating law with stable, non-instrumental rules turned it into a non-human mechanism. That conclusion provoked a reaction against what was described as “mechanical jurisprudence,” which culminated in an attack on the identification of law with rules, an identification which has since become known as legal formalism. The attack moved on to blur or deny the distinction between legislation and adjudication, and ultimately to a repudiation of the traditional idea of law.

Friedrich Karl von Savigny

At first, however, the reaction against mechanical jurisprudence took the innocuous shape of a new interest in the historical character of legal systems. Friedrich Karl von Savigny, who initiated this development with his studies in Roman law, did not in any way challenge the traditional idea of law. What he opposed was the disposition to liken law to a system of mathematics that can be deduced from axioms, an analogy that appealed to those who saw in codification the universal remedy for all defects in a legal system.