A more thorough explanation:

An Article I court is a type of federal court that is not bound by the requirements of or protected under U.S. Constitution Article III, Section 2. It performs functions similar to those of an administrative agency, such as issuing advisory opinions.

Congress has the power to create Article I courts within certain limits. These courts are akin to administrative agencies, and the judges do not have any constitutionally guaranteed lifetime tenure and protection from salary diminution. They are not governed by the case or controversy limitation of Article III.

Examples of Article I courts include:

• Territorial courts
• Certain courts in the District of Columbia
• Courts martial
• Legislative courts and administrative agencies that adjudicate "public rights"

For instance, territorial courts are established in U.S. territories and are responsible for hearing cases that arise under local law. Courts martial are military courts that try members of the armed forces for violations of military law. Legislative courts are created by Congress to hear cases related to specific legislative matters, such as tax disputes or patent claims.