The role of the judicial branch in the United States government is that of fulfilling Article IIl of the U.S. Constitution, which invests power in the Supreme Court. Congress may also see fit to establish other inferior courts. Federal judges are judges for life or until retirement, unless there is an incident of impeachment.
The president appoints the judges in the judiciary branch. The U.S. Senate then confirms them. The appointment of the judges differs in method from those of the executive and legislative branches of government. The citizens of the U.S. elect the legislative and executive branches.
The highest court in the U.S. is the Supreme Court. Any decision arrived at by the Supreme Court is without appeal. The Supreme Court generally does not hold trials but interprets the meaning of a law.