Dear John Roberts, Chief Justice of the Supreme Court, your presence is required in the Senate for the trial of Donald John Trump when it commences next month.
You may naively believe you can skip this trial because Mr. Trump is out of office. Nothing could be further from the truth. The Constitution says, and I quote:
The Senate shall have the sole Power to try all Impeachments. When sitting for that Purpose, they shall be on Oath or Affirmation. When the President of the United States is tried, the Chief Justice shall preside: And no Person shall be convicted without the Concurrence of two thirds of the Members present.
[Article I, Section 3, Paragraph 6]
This passage is intended to distinguish trials for the President from trials for the Vice President and from trials for civil Officers of the United States. [Article II, Section 4]. Trump is on trial because he was President when he committed the treason, bribery, and high crimes and misdemeanors that justify impeaching him. He is being tried as President of the United States. Therefore, the Chief Justice shall preside.
That means you, Mr. Roberts. When the trial starts in February you will get your black-robed duff over there and do your job.
Or resign.