Branch of government in which judicial power is vested. The principal work of any judiciary is the adjudication of disputes or controversies. Regulations govern what parties are allowed before a judicial assembly, or court, what evidence will be admitted, what trial procedure will be followed, and what types of judgments may be rendered. Typically present in court are the presiding judge, the parties to the matter (sometimes called litigants), the lawyers representing the parties, and other individuals including witnesses, clerks, bailiffs, and jurors when the proceeding involves a jury. Though the courts' stated function is to administer justice according to rules enacted by the legislative branch, courts also unavoidably make law. In deciding, for example, how legislative provisions are to be applied to specific cases, the courts in effect make law by laying down rules for future cases; this is known as the doctrine of precedent. In some jurisdictions, courts have the power of judicial review, enabling them to declare unconstitutional legislation or acts of the executive.

Learn more about judiciary with a free trial on Britannica.com.

The term is also used to refer collectively to the judges, magistrates and other adjudicators who form the core of a judiciary, as well as the support personnel who keep the system running smoothly. Under the doctrine of the separation of powers, the judiciary is the branch of government primarily responsible for interpreting the law. It construes the laws enacted by the legislature.

• In common law jurisdictions, courts interpret law, including constitutions, statutes, and regulations. They also make law based upon prior case law in areas where the legislature has not made law. For instance, the tort of negligence is not derived from statute law in most common law jurisdictions. The term common law refers to this kind of law.
• In civil law jurisdictions, courts interpret the law, but are, at least in theory, prohibited from creating law, and thus, still in theory, do not issue rulings more general than the actual case to be judged. In practice, jurisprudence plays the same role as case law.
• In socialist law, the primary responsibility for interpreting the law belongs to the legislature.

This difference can be seen by comparing United States, France and the People's Republic of China:

• in the United States government, the Supreme Court is the final authority on the interpretation of the federal Constitution and all statutes and regulations created pursuant to it;
• in France, the final authority on the interpretation of the law is the Conseil d'État for administrative cases, and the Court of Cassation for civil and criminal cases;
• and in the PRC, the final authority on the interpretation of the law is the National People's Congress.
• Other countries such as Argentina have mixed systems that include lower courts, appeals courts, a cassation court (for criminal law) and a Supreme Court. In this system the Supreme Court is always the final authority but criminal cases have four stages, one more than civil law.

It is said that the famed Byzantine Emperor Justinian had the Corpus Juris Civilis compiled and all other decisions by jurists burned to create certainty in the law. Again in the 19th century, French legal scholars at the time of the development of the Code Napoléon advocated the same kind of approach — it was believed that since the law was being written down precisely, it should not need interpretation; and if it did need interpretation, it could be referred to those who wrote the code. Napoleon, who was an advocate of this approach, felt that the task of interpreting the law should be left with the elected legislature, not with unelected judges. This contrasted with the pre-revolutionary situation in France, where unelected 'parliaments' defending the interests of the nobility would often slow the enforcement of royal decisions, including much needed reforms.

However, this idea was found difficult to implement in practice. In France, along with other countries that Napoleon had conquered, or where there was a reception of the Civil Code approach, judges once again assumed an important role, like their English counterparts. In civil law jurisdictions at present, judges interpret the law to about the same extent as in common law jurisdictions – though it may be acknowledged in theory in a different manner than in the common law tradition which directly recognizes the limited power of judges to make law. For instance, in France, the jurisprudence constante of the Cour de cassation or the Conseil d'État is equivalent in practice with case law.

In theory, in the French civil law tradition, a judge does not make new law; he or she merely interprets the intents of "the Legislator." The role of interpretation is traditionally approached more conservatively in civil law jurisdictions than in common law jurisdictions. When the law fails to deal with a situation, doctrinal writers and not judges call for legislative reform, though these legal scholars sometimes influence judicial decisionmaking. So-called "Socialist" law adopted the status of civil law, but added to it a new line of thought derived from Communism — the interpretation of the law is ultimately political, and should serve the purposes of Communism, and hence should not be left to a non-political organ.

See also

• Separation of powers
• Executive
• Legislature
• Judiciaries