“Chief Justice Roberts sits. The Presiding Officer makes the rules. “
Possible behind the scenes dynamic:
https://theconservativetreehouse.com/2019/12/05/the-senate-and-impeachment-dynamic/
How the trial is conducted:
https://nclawyersweekly.com/2019/10/30/ap-explains-what-a-trump-impeachment-trial-might-look-like/
I do not often cite conservative radio host Mark Levin, but today is that day: