The judiciary is the system of courts that interprets, defends and applies the law in the name of the state. The judiciary can also be thought of as the mechanism for the resolution of disputes. Under the doctrine of the separation of powers, the judiciary generally does not make statutory law (which is the responsibility of the legislature) or enforce law (which is the responsibility of the executive), but rather interprets law, defends and applies it to the facts of each case. However, in some countries the judiciary does make common law.
In many jurisdictions the judicial branch has the power to change laws through the process of judicial review. Courts with judicial review power may annul the laws and rules of the state when it finds them incompatible with a higher norm, such as primary legislation, the provisions of the constitution, treaties or international law. Judges constitute a critical force for interpretation and implementation of a constitution, thus in common law countries creating the body of constitutional law.
Functions of The Judiciary
In common law jurisdictions, courts interpret law; this includes constitutions, statutes, and regulations. They also make law (but in a limited sense, limited to the facts of particular cases) 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. Common law decisions set precedent for all courts to follow. This is sometimes called stare decisis.
In civil law jurisdictions, courts interpret the law, but are prohibited from creating law, and thus do not issue rulings more general than the actual case to be judged. In other words, they do not set precedent. Jurisprudence does not necessarily play a similar role to case law. Courts can decide if they follow jurisprudence in a given case or not.
In the United States court system, the Supreme Court is the final authority on the interpretation of the federal Constitution and all statutes and regulations created pursuant to it, as well as the constitutionality of the various state laws; in the US federal court system, federal cases are tried in trial courts, known as the US district courts, followed by appellate courts and then the Supreme Court. State courts, which try 98% of litigation, may have different names and organization; trial courts may be called “courts of common plea”, appellate courts “superior courts” or “commonwealth courts”. The judicial system, whether state or federal, begins with a court of first instance, is appealed to an appellate court, and then ends at the court of last resort.