Article III of the Constitution establishes the judicial branch of the national government, which is responsible for interpreting the laws. At the highest level, the judicial branch is led by the U.S. Supreme Court, which consists of nine Justices. In the federal system, the lower courts consist of the district courts and the courts of appeals. Federal courts—including the Supreme Court—exercise the power of judicial review. This power gives courts the authority to rule on the constitutionality of laws passed (and actions taken) by the elected branches. The Constitution also promotes the principle of judicial independence—granting federal judges life tenure (meaning that they serve until they die, resign, or are impeached and removed from office). This module will examine the judicial branch and its powers.