In which court level is the highest authority located in the federal court system?

The highest authority in the federal court system is located in the Supreme Court. As the ultimate arbiter of federal law, the Supreme Court has the power to interpret the Constitution and federal statutes, setting precedents that lower courts are required to follow. This court hears cases on significant issues, often involving disputes over federal law, and its decisions can only be overturned by the Court itself or through constitutional amendments.

The District Court serves as the trial courts of the federal system, where most federal cases start, but they do not hold the highest authority. Similarly, the Court of Appeals acts as an intermediary appellate court that reviews decisions made by District Courts, while Circuit Courts can refer to various levels of courts in different contexts, often at the state level, which do not apply to the federal hierarchy. Therefore, the Supreme Court is the correct answer, as it maintains the highest level of judicial authority in the federal judiciary.