Unwritten rules, principles, and norms that have the effect and force of law though they have not been formally enacted by the government.
Most laws in America are written. The U.S. CODE, the CODE OF FEDERAL REGULATIONS, and the Federal Rules of Civil Procedure are three examples of written laws that are frequently cited in federal court. Each state has a similar body of written laws. By contrast, unwritten law consists of those customs, traditions, practices, usages, and other maxims of human conduct that the government has recognized and enforced.
Unwritten law is most commonly found in primitive societies where illiteracy is prevalent. Because many residents in such societies cannot read or write, there is little point in publishing written laws to govern their conduct. Instead, societal disputes in primitive societies are resolved informally, through appeal to unwritten maxims of fairness or popularly accepted modes of behavior. Litigants present their claims orally in most primitive societies, and judges announce their decisions in the same fashion. The governing body in primitive societies typically enforces the useful traditions that are widely practiced in the community, while those practices that are novel or harmful fall into disuse or are discouraged.
Much of INTERNATIONAL LAW is a form of primitive unwritten law. For centuries the RULES OF WAR governing hostilities between belligerents consisted of a body of unwritten law. While some of these rules have been codified by international bodies such as the UNITED NATIONS, many have not. For example, retaliatory reprisals against acts of TERRORISM by a foreign government are still governed by unwritten customs in the international community. Each nation also retains discretion in formulating a response to the aggressive acts of a neighboring state.
In the United States, unwritten law takes on a variety of forms. In CONSTITUTIONAL LAW the Supreme Court has ruled that the DUE PROCESS CLAUSE of the Fifth and Fourteenth Amendments to the U.S. Constitution protects the right to privacy even though the word privacy is not mentioned in the written text of the Constitution. In COMMERCIAL LAW the UNIFORM COMMERCIAL CODE permits merchants to resolve legal disputes by introducing evidence of unwritten customs, practices, and usages that others in the same trade generally follow. The entire body of COMMON LAW, comprising cases decided by judges on matters relating to TORTS and contracts, among other things, is said to reflect unwritten standards that have evolved over time. In each case, however, once a court, legislature, or other government body formally adopts a standard, principle, or MAXIM in writing, it ceases to be an unwritten law.