Law is the set of rules that a particular society or community recognizes as regulating its members’ behavior. It is the basis for many social and political institutions. Law can be created and enforced in a variety of ways, including by legislation (in the form of statutes and regulations); executive decrees; or judicial interpretations of precedent, as in the case of common law jurisdictions. Law may also be written and ratified by private individuals, in the form of contracts, for example. Law may govern a range of subjects, from contracts and property to criminal activity and the environment.
The precise definition of law is a subject of longstanding debate, and differs from person to person. It is a central concept in legal studies and practice, but its significance extends far beyond that sphere. A fundamental question is whether a system of laws can serve its purpose, which is generally understood as being to keep the peace, maintain the status quo, preserve individual rights, protect minorities against majorities, and promote social change in an orderly way. The answer to this question depends on the political structure that defines a state and the system of law that it adopts. For example, an authoritarian regime might keep the peace and maintain the status quo, but oppress minorities or opposition groups, while a democratic regime might encourage peaceful social change through the rule of law.
In the United States, federal and state law each cover a wide array of topics. The laws at the state level are often more detailed, and can differ widely from those of the federal government, especially in areas such as civil rights and the environment. Federal laws can preempt state laws in certain areas, such as aviation and railroads, but in other cases they coexist with each other, for instance in patent law and family law.
A specialized field of law is constitutional law, which examines how a state’s constitution provides the framework for its legal systems. Other broad fields of law include criminal law, contract law, property law, and tort law. The article outlines the basic principles and concepts of each, but for more information on specific issues see related articles: