The judiciary (also known as the judicial system or judicature) is the system of courts that interprets and applies the law in the name of the sovereign or state. The judiciary also provides a mechanism for the resolution of disputes. Under the doctrine of the separation of powers, the judiciary generally does not make law (that is, in a plenary fashion, which is the responsibility of the legislature) or enforce law (which is the responsibility of the executive), but rather interprets law and applies it to the facts of each case. This branch of government is often tasked with ensuring equal justice under law. It usually consists of a court of final appeal (called the "supreme court" or "constitutional court"), together with lower courts.
In most 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 the provisions of a constitution. Judges constitute a critical force for interpretation and implementation of a constitution, thus de facto in common law countries creating the body of constitutional law. (http://en.wikipedia.org/wiki/Judiciary)