And so I quote directly from AM:
Moreeover, because the Constitution wholly vests the process of impeachment in the House, and the conduct of impeachment trials in the Senate, those chambers have plenary authority over the respective proceedings. No court has the power to tell the House or Senate what quantum of due process must be afforded to an official in an impeachment case. No one can make Congress apply the Sixth Amendment.
Finally, even when the Sixth Amendment does apply (at a criminal trial), the confrontation it guarantees is the ability to cross-examine the witnesses the prosecution calls to establish its case. It does not extend to other people (e.g., tipsters, others who’ve provided hearsay information to investigators). It is very common in the investigative stage for police to receive damning information about a suspect from second- and third-hand sources. That information is investigated, which is how the police and prosecutors locate the first-hand witnesses who are called at the eventual trial. There is no right to confront witnesses the prosecutor does not call, even if they have provided accusatory information.
This goes directly to the multiple times the President he has both a right of confrontation and that he is not being afforded due process-he is not. Constitutional protections for due process apply when the state is attempting to deprive a person of “life, liberty, or property.” That’s why we have trials before we render civil or criminal judgments. That’s why due process is mandatory before state-mandated punishment in campus sexual assault tribunals. As a general rule, when the state is attempting to deprive you of rights you’d otherwise enjoy, due process attaches—that is not the case at present.