Legislation comprises the rules of law adopted by agencies of government to regulate social behavior. The term is commonly used specifically for the laws enacted by representative assemblies, as well as for the process of enacting laws.
Natural Law and Legal Codes
Legislation, defined in this way, is a product of the modern state and of representative systems of government, but it has roots in Greek and Roman history. The ancient Greeks were concerned with natural law, the moral standards of justice that should govern society, but they also enacted specific laws to regulate social behavior and governmental activity. During the Roman era, an elaborate system of laws was developed, and during the reign of Emperor Justinian these laws were codified. In the Middle Ages the concept of natural law acquired a Christian foundation, and the canon law of the Roman Catholic Church overshadowed Roman law. But the Justinian Code had a strong influence on the legal codes developed in Europe at the end of the Middle Ages.
Statutory, Common, and Constitutional Law
With the development of the modern state, the authority for legislating was centralized in the national government. With the development of representative assemblies as independent, authoritative law-making bodies, the term legislation (or statutory law) was applied to the enactments of these assemblies.
On the European continent, legal codes based on Roman law and the Napoleonic code cover both civil and criminal law. In the English-speaking world the legal system is based on common law, the precedents, established by judges, dating from early in English history. By the 17th century it became clear that statutes adopted by the British Parliament were superior to, that is, took precedence over, the common law. As modern governments have been expected to play an increasingly active role in regulating economic and social life, statutory law has assumed greater importance, compared with common law. This is true in the United States and Britain.
It is also important to distinguish between constitutional and statutory law in the United States and in other countries that have a written constitution. The provisions of a written constitution, defining the political organization of a state and establishing limits oij the exercise of political power, are considered superior to statutory law, or legislation. In the United States the courts ensure that legislation will be compatible with constitutional law by exercising judicial review over legislation. The constitutions of many states of the United States contain detailed provisions that are "legislative" in nature and that consequently limit the jurisdiction of state legislatures.
As government has grown more complex, national and state legislative bodies have found it necessary to enact broadly written statutes and to delegate a large measure of rule-making authority to executive agencies and commissions as well as to local units of government. The rules adopted by such bodies are sometimes referred to as secondary legislation.