Who establishes federal courts lower than the Supreme Court?

Congress

Both Article I, Section 8 and Article III, Section 1 of the Constitution assigned authority for creating the federal courts to Congress, or the Legislative branch. This allows Congress to establish Courts and tribunals that are part of the Judicial Branch (constitutional courts), as well as courts of limited jurisdiction that operate outside the Judicial Branch.

Article III (constitutional) Courts comprise the Judicial Branch of government. All other federal courts fall outside the Judicial Branch.

Article III, Section 1:

"The judicial power of the United States, shall be vested in one Supreme Court, and in such inferior courts as the Congress may from time to time ordain and establish. The judges, both of the supreme and inferior courts, shall hold their offices during good behaviour, and shall, at stated times, receive for their services, a compensation, which shall not be diminished during their continuance in office"

The phrase "and in such inferior courts as the Congress may from time to time ordain and establish" indicates the Framers intended Congress to have authority to create, dismantle, assign jurisdiction, vary court size, and make other unspecified changes at their discretion, unless the Constitution dictates otherwise.

Current Article III Courts

• US District Courts
• US Court of International Trade
• US Court of Appeals Circuit Courts
• Supreme Court of the United States

Article I, Section 8:

"[Congress shall have the power] [t]o constitute tribunals inferior to the Supreme Court"

Examples of Article I Courts

• US Court of Federal Claims
• US Bankruptcy Court
• US Tax Court
• US Court of Appeals for the Armed Forces