Is an unjust law still a law? Legal philosophers still disagree
An old maxim says an unjust law is no law at all. Natural law thinkers from Aristotle through Thomas Aquinas broadly agreed, holding that valid law must answer to reason and morality. Legal positivists reply that law is simply whatever a society's institutions recognise as law, good or bad, and the argument continues.
Jurisprudence, also called legal theory, applies philosophy to questions such as what law is and what it should be. The English word dates from 1628, from the Latin for expertise in law. In civil law countries, however, jurisprudence usually means case law, and the philosophy goes by legal theory or legal science. Signs of such thinking appear in the fifth century BCE in Greece, India and China, and in the work of Confucius, Aristotle and Augustine, though these writers treated justice as part of broader ethics.
Natural law grounds legal validity in human nature and the rights that flow from it. Cicero called true law right reason in agreement with nature, and Aquinas built Aristotle's ideas into classical natural law theory, which shaped canon law, international law and social contract thinking. Enlightenment critics such as Hume, Hobbes and Bentham attacked it, but John Finnis revived a new version in the twentieth century, and appeals to human rights still lean on similar reasoning.
The rival tradition began with command theories. Hobbes, and later John Austin, described law as a sovereign's orders backed by threats and habitually obeyed. Positivism went on to dominate, holding that law's content rests on social facts, not moral merit. H. L. A. Hart refined it by distinguishing primary rules, which impose duties, from secondary rules that say how laws are made, changed and applied, anchored by a rule of recognition practised by judges and officials.
A third strand saw law as custom. English common law courts long claimed merely to discover rules existing since time immemorial, and Friedrich Carl von Savigny argued that Germany lacked the shared traditions a legal code would need. In the United States, scholarship leans instead toward legal realism and social science, treating legal reasoning as shaped by power and policy.
Source: Jurisprudence
