Sources of law

The origins of law are the binding rules that allow a state to govern its territory. Cicero used the term in ancient Rome as a metaphor, calling law a "fountain" (from the Latin *fons*). In a technical sense, anything that can establish, alter, or abolish a right or law qualifies as a source of law. The phrase can also point to the sovereign or the seat of power that gives law its validity.

Legal theory typically divides sources into formal and material categories, though this classification is not always applied consistently. Formal sources are generally linked to what creates law—statutes, case law, and contracts, for example. Material sources, by contrast, are the places where formal law can be found, such as official bulletins or gazettes where a legislature publishes a country's laws, newspapers, and public deeds. Drawing on Aristotle’s concept of four causes (material, formal, efficient, and final), Riofrio identifies additional potential sources. Efficient sources include actions of nature or "of God" that change law, intellectual actions that produce legal culture, and willful actions that approve laws and agreements. Final sources encompass the purposes of law, the intentions of parties in a legal transaction, the goals of each policy, and the ends of a constitution.

The perceived legitimacy of a source of law can depend on a choice of jurisprudence analysis. A tyrant like Kim Jong-un may hold *de facto* power, but critics argue he does not exercise it from a *de jure* (or legitimate) source. After World War II, the defense "I was only obeying orders" failed at Nuremberg, and the victors executed Nazis for violating "universal and eternal standards of right and wrong." Over centuries, principles of law have emerged from customs. Early unwritten sources include the divine right of kings, natural and legal rights, human rights, civil rights, and common law. Historical or judicial precedent and case law can modify or create a source of law. Legislation, rules, and regulations form the tangible, codified, and enforceable sources.

In civil law systems, sources include legal codes—such as civil or criminal codes—and custom. Common law systems combine several sources to form "the law." Civil law often absorbs ideas from common law and vice versa. Scotland and South Africa, for example, have hybrid legal systems; South Africa’s law blends common law, civil law, and tribal law. A state may follow international law, have a written or federal constitution, or include regional legislatures, but the central national legislature is typically the ultimate source of law. Even a written constitution can be amended by the state legislature if certain rules are followed. International law may override national law, but it mainly consists of conventions and treaties that have been ratified, and anything ratified can later be denounced by the national parliament. Local authorities may believe they have a democratic mandate to pass by-laws, but their legislative power is delegated by parliament, and what parliament gives, it can take away.

In England, the archetypal common law country, sources are ranked in a hierarchy: legislation (primary and secondary), case law rules of common law and equity, parliamentary conventions, general customs, books of authority. Canon law and other religious law form the basis for law derived from religious practices, doctrines, or sacred texts; this source is important where a state religion exists.

International treaties become binding only after ratification. Most conventions take effect when a stated number of signatories have ratified the final text. An international convention may be incorporated into a statute—for example, the Hague–Visby Rules in the Carriage of Goods by Sea Act 1971, or the Salvage Convention in the Merchant Shipping Act 1995. The European Convention on Human Rights, from the Council of Europe, is enforced by the European Court of Human Rights in Strasbourg.

The European Union is a special case of international law. Nations joining the EU adopt all existing EC law (the *acquis communautaire*), including treaty provisions, regulations, directives, decisions, and precedents. Member states become subject to "Brussels" and to the binding precedent decisions of the Court of Justice of the European Union (CJEU) in Luxembourg. However, Brussels may only act and legislate according to the EU treaties, and the CJEU’s supremacy applies only in matters of EU law.

Legislation is the prime source of law, consisting of legal rules declared by a competent authority. It serves many purposes: to regulate, authorize, enable, proscribe, provide funds, sanction, grant, declare, or restrict. A parliamentary legislature frames new laws, such as acts of Parliament, and amends or repeals old ones. It may delegate law-making powers to lower bodies. In the UK, delegated legislation includes statutory instruments, Orders in Council, and bye-laws. Such legislation can be challenged for procedural irregularity, and the legislature usually retains the right to withdraw delegated powers. Most legislatures are constrained by a nation’s constitution, and Montesquieu...