What determines the term of office for US Supreme Court justices?
According to Article III, Section I, of the Constitution, Supreme Court justices hold their offices "during good behavior," meaning for life, as long as they don't commit an impeachable offense. Qualifying infractions are defined in Article II, Section 4, as "treason, bribery, or other high crimes and misdemeanors."
There are nine justices on the US Supreme Court -- one Chief Justice and eight Associate Justices -- who review cases as a group. Congress determines the number of justices needed and formally adjusts the size of the Court via a Judiciary Act, which is ordinary legislation affecting the federal court system. The size of the current Supreme Court was set by the Judiciary Act of 1869.
The Supreme Court of the United States seats nine justices. Some states may seat seven or even fewer. Congress determines the number of justices primarily on the basis of how many they believe are needed to handle the Court's caseload and other responsibilities.The number of US Supreme Court justices has not changed since the Judiciary Act of 1869.
Congress fixes the salaries of all federal officials in the same way that it passes laws in other matters. The bill setting salaries is passed by both the House of Congress, then it is sent to the President for his approval. Salaries of the Supreme Court justices may not be reduced once an individual justice takes office
US Supreme Court justices serve "during good behavior," meaning they are entitled to hold office for life unless unless they commit an impeachable offense; therefore, there is no standard appointment schedule. New justices are nominated when there is a vacancy on the Supreme Court due to the retirement, resignation, death or impeachment of one or more sitting justices.