nder the Constitution, the President appoints federal judges with the "advice and consent" of the Senate. The President usually consults senators or other elected officials concerning candidates for vacancies on the federal courts. The President's power to appoint new federal judges is not the judiciary's only interaction with the executive branch. The Department of Justice, which is responsible for prosecuting federal crimes and for representing the government in civil cases, is the most frequent litigator in the federal court system. Several other executive branch agencies affect the operations of the courts. The United States Marshals Service, for example, provides security for federal courthouses and judges, and the General Services Administration builds and maintains federal courthouses. Within the executive branch there are some specialized subject-matter courts, and numerous federal administrative agencies that adjudicate disputes involving specific federal laws and benefits programs. These courts include the United States Tax Court, the United States Court of Military Appeals, and the United States Court of Veterans Appeals. Although these courts and agencies are not part of the judiciary established under Article III of the Constitution, appeals of their decisions typically may be taken to the Article III courts.