Can the Chief Justice be demoted to Associate Justice of the Supreme Court?
Let's suppose that, during a presidency, enough justices retire, making it possible for the president to appoint new justices which would give the Supreme Court a different ideological majority.
Would the president have the legal ability to demote the incumbent chief justice to associate justice, and to appoint a new chief justice, more in accordance with the ideology of the new majority of the Court?
Is the Chief Justice position attached to the perceived ideological balance of the Court?
The Chief Justice position is a constitutional grey area.
The US constitution does not mention how that position is appointed. It in fact only acknowledges its existence in a single sentence regarding presidential impeachment (Article I, Section 3, Clause 6: "When the President of the United States is tried, the Chief Justice shall preside.").
There are political scholars who argue that the President should not have the right to appoint someone explicitly for the Chief Justice position and the Supreme Court should choose the Chief Justice from among them. But so far no Supreme Court has ever tried this.
If the president would step into that grey area and try to replace the Chief Justice, then the Supreme Court would also be in the position to decide if that is constitutional. If they come to a decision, that decision would then likely properly codify the procedure for choosing the Chief Justice in the future.
This seems right as far as it goes, but also incomplete. The Constitution also doesn't specify the size of the court - that's up to Congress. So are there any relevant non-Constitution laws? Even a "nothing has ever addressed it" would finish this off.
Regardless of the lack of specificity in the Constitution, even mentioning the existence of a Chief Justice presupposes the existence of such a title, and all federal judicial appointments come without term limitations. The chief justice isn't just appointed, but has to be confirmed, specifically for that position, by the US Senate under the Appointments Clause of the US Constitution. There would be no way for anyone to try and unseat a sitting Chief Justice outside of impeachment, just like with all the other federal judicial appointments.
@PoloHoleSet: I'm not sure it's that easy. Presidents have in the past elevated Associate Justices to Chief, but that would seem problematic if you assume their initial appointments were "for life."
@Kevin any associate justice can resign for any reason, including to accept an appointment as chief justice.
@Kevin - It really isn't problematic. ASomeone at the federal circuit or appeals level is appointed for life. They relinquish that position, voluntarily, as phoog mentioned, to accept a position with the Supreme Court. That came into play with the Kavanaugh appointment and complaints filed about his testimony before the Senate - Roberts held on to them until he was confirmed, then passed them to one of the courts to "investigate," and, as expected, they said "we have no jurisdiction over this because he's now a federal judge at the SCOTUS level, which we have no authority over."