Final answer:
Article III of the U.S. Constitution establishes the Judicial Branch and grants it the judicial power, mainly through appellate jurisdiction, with the Supreme Court at its head. The Constitution and subsequent Judiciary Act of 1789 set the framework for the court system and allow Congress to determine the number of Supreme Court justices, which is currently nine.
Step-by-step explanation:
Article III of the U.S. Constitution establishes the Judicial Branch and grants judicial power to one Supreme Court. It also allows for the creation of inferior courts and grants Congress the authority to determine their structure. While Article III provides the Supreme Court with original jurisdiction in certain rare instances, such as disputes between states, it mainly exercises appellate jurisdiction, handling appeals from lower courts.
The Supreme Court's role as the highest court ensures its decisions set legal precedents, impacting civil liberties and rights. The number of justices has changed over time, with the current number being nine since 1869. Article III's generality was fleshed out by the Judiciary Act of 1789, which structured the federal judiciary system.