By What Lawful Authority
As I mentioned yesterday, the current situation with the faux impeachment has historical analogies. Of particular note is the trial of King Charles I in England in the 17th Century by radical members of Parliament. Oliver Cromwell was a prominent leader of Parliament who was directly engaged in the insurrection that defeated King Charles. And it was an insurrection.
While this is a long story involving multiple years of civil war in England, in the end the dispute was about powers that Parliament had versus the powers of the King.