Proposing an amendment to the Constitution of the United States to require that the Supreme Court of the United States be composed of nine justices.

The joint resolution would propose a new constitutional amendment stating that the Supreme Court of the United States shall be composed of nine justices — one chief justice and eight associate justices. Because it is a proposed constitutional amendment rather than ordinary legislation, it would need to pass both chambers of Congress by a two-thirds vote and then be ratified by the legislatures of three-fourths of the states within seven years of submission to become part of the Constitution. The resolution does not change the current number of justices, which is already nine by federal statute; it would instead enshrine that number in the Constitution itself, making it much harder for a future Congress to expand or shrink the Court through ordinary law.

The Supreme Court and its current and future justices, Congress (which would need to pass any future legislation to change the Court's size), and state legislatures, which would need to ratify the amendment for it to take effect.

If ratified, the amendment would permanently bar Congress from changing the number of Supreme Court justices through ordinary legislation, foreclosing any future effort to expand or reduce the Court's membership without another constitutional amendment. This would directly affect ongoing political debates about "court packing."

As a proposed constitutional amendment, the resolution itself would take no legal effect upon passage by Congress. It would first need approval by two-thirds of both the House and Senate, then be submitted to the states for ratification. The amendment would become part of the Constitution only if three-fourths of state legislatures (currently 38 of 50) ratify it within seven years of submission; otherwise it would lapse.