For Trump’s post-presidency Senate trial, I tentatively think, as a matter of constitutional interpretation, that the Chief Justice should preside.
It’s a reasonable question: “When the President of the United States is tried, the Chief Justice shall preside.” After Jan 20, Trump is no longer “President,” even if the misconduct was during his presidency. If he is not “the President,” then the presidential exception seemingly does not apply to former presidents, and the default rule stands: The Vice President presides.
But formalistic textualism is not the most appropriate method for the interpretation of concise (laconic and often deliberately abstract or inevitably imprecise) constitutional texts, even if it may be the best approach for the “prolixity” of statutes. The best reading of Artice I, Sec. 3 is first, originalist/purposivist: It’s not just the direct conflict problem for VP to preside in removal. Trying presidential conduct is fraught w/ political, partisan & personal conflicts.
Second, if one tries to apply the more formalistic/textual argument that a former president is no longer “president” (and, yes, that’s true), there is still a textual practical reading for the Chief to preside: In a normal Senate trial, who would preside during any *disqualification stage* after removal vote? When the sitting president has already been removed? He/she would be formally no longer the president. The formalistic textual reading (the Chief presides only for formally sitting presidents) would lead to the strange conclusion that the Chief Justice can never preside over Disqualification, even after presiding over the entire trial up to that point. The impeached president has been removed, and thus is no longer technically/formally “President of the United States.” Moreover, the vice president has been transformed into the President. Thus, according to the strict formalist textualist reading, the Chief Justice may never preside over the disqualification stage, and after a presidential removal, there is formally no Vice President anymore. So there is no Vice President left to preside.
Maybe a solution in the DQ stage for a just-removed president is the Senate chooses one of its own to preside (officer like Pro Tem). But that solution creates other problems: A “juror” would also be presiding as judge? It’s not a criminal trial, but this dual role would be an odd situation.
Thus, the best reading that is most consistent with the original constitutional principles and that makes common sense of the text in practice is that the Chief Justice should preside over an impeachment of presidents and former presidents.