The Judicial Branch
The Judicial Branch, or the Judiciary, is responsible for explaining and applying laws. It is the highest court in the United States. Cases in lower courts that are repeatedly appealed to higher courts will eventually meet with the Supreme Court, which will determine a final judgement. It is often the Supreme Court that establishes precedent. Such cases include 1973s Roe v Wade - where the court found that laws preventing access to abortion was a violation of a right to privacy - and 1966s Miranda v Arizona - where the court ruled that evidence gathered and questions asked prior to a defendant understanding his rights are not admissible.
Article III Section I of the Constitution established the Supreme Court and gave it the authority to establish lower courts as needed. The same section details that judges appointed to the Supreme Court are not subject to term limits, and may serve for the remainder of their lives. Originally set at six by the Judiciary Act of 1789, there are now nine serving Supreme Court Justices, all of which are appointed by a President of the United States.
The Judiciary Act is also responsible for dividing the nation inso judicial districts and creating federal courts for each district. The structure of the national court system includes The Supreme Court, 13 court of appeals, 94 district courts, and two special jurisdiction courts. Congress holds the power to abolish lower courts.
The powers of the Supreme Court include the settlement of disputes between states, matters pertaining to the federal government, and the power of judicial review, which allows the Supreme Court to declare any legislation or executive action unconstitutional, effectively nullifing the law and creating precedent for future rulings. This power was put in place by Chief Justice Marshall in the case of Marbury v Madison in 1803, which formed the basis for the exercise of judicial review.
The three levels of federal courts inferior to the Supreme Court are, from most powerful to least, courts of appeals, district courts, and special jurisdiction courts.
Specialized courts exist to handle cases involving bankruptcy and taxation disputes, and are under the supervision of the district courts. District courts are trial courts where cases that are under the Judicial Code (Title 28 of the United States Code) can be filed and decided. These courts often serve as the first court to decide on alleged common misdemeanors and felonies. The court of appeals, or appellate courts, hear appeals of cases that are already decided by district courts. In turn, the U.S. Supreme Court will hear appeals from decisions made by a court of appeals.