What is the length of a federal judge's term?

Federal judges serve lifetime appointments, meaning they hold their positions for life, unless they choose to retire, resign, or are removed through impeachment. This system is established in the U.S. Constitution to ensure judicial independence, allowing judges to make decisions based on the law without political pressure. The lifetime tenure is intended to protect the integrity of the judiciary and to maintain a stable and consistent interpretation of the law, as it enables judges to operate free from the influence of politics or public opinion.

In contrast, the other options do not align with the established federal judicial system. Federal judges do not have fixed terms like some state and local judges or elected officials, which is why a term of 4 years, 10 years, or 20 years would not apply to them. The lifetime appointment is a key feature that distinguishes federal judges from other positions in the government.