The United States Sentencing Commission is an independent agency of the judicial branch of the federal government of the United States. It is responsible for articulating the sentencing guidelines for the United States federal courts. The Commission promulgates the Federal Sentencing Guidelines, which replaced the prior system of indeterminate sentencing that allowed trial judges to give sentences ranging from probation to the maximum statutory punishment for the offense. The commission was created by the Sentencing Reform Act provisions of the Comprehensive Crime Control Act of 1984. The constitutionality of the commission was challenged as a congressional encroachment on the power of the executive but upheld by the Supreme Court in Mistretta v. United States, 488 U.S. 361 (1989). Unlike many special-purpose "study" commissions within the executive branch, Congress established the U.S. Sentencing Commission as a permanent, independent agency within the judicial branch. The seven voting members on the Commission are appointed by the President and confirmed by the Senate, and serve six-year terms. Commission members may be reappointed to further terms with the consent of the Senate. No more than three of the commissioners may be federal judges, and no more than four may belong to the same political party. The United States Attorney General and the chair of the United States Parole Commission sit as nonvoting ex officio members of the Commission.