First is whether the impeachment trial is a civil or criminal proceeding. Second is what the Quantum of Evidence and Proof are required to convict. Though Fr. Bernas claims to be exasperated with the term, I'm quite comfortable with impeachment being a sui generis process, whose nature, practices and rules of procedure are evolving with the institution as the Congress learns how to wield the special Constitutional powers of impeachment granted exclusively and solely to the House and Senate. The Rules of Senate and House, separately and together with the orders, rulings, proceedings, records, testimonies relating to the Senate Impeachment Court and the trial of the accused Chief Justice Renato Corona are now the body of jurisprudence and official record by which we are giving life to Article XI of the 1987 Constitution on Accountability of Public Officers.
By itself, the text of the 1987 Constitution is necessarily too thin and laconic, to satisfy the intellectual demands of Constitutionalists and ordinary citizens that impeachment be better defined. But look at 1987.XI.Sec3(8):
(8) The Congress shall promulgate its rules on impeachment to effectively carry out the purpose of this section.Like a magical link, this provision empowers the House and Senate to literally create whatever RULES on impeachment they need to "effectively carry out the purpose" of impeachment. The evolution, adoption and utilization of these Rules are a matter of public interest and record and should be open to public debate like any other important matter of public policy.
Fr. Bernas also addressed the matter of what penalties go with conviction by the Senate Impeachment Court. He does not answer a question I still don't have a good answer to: what happens if Accused CJ resigns before a verdict is pronounced. He clearly vacates his post, but is a permanent lifetime ban automatically attached to resignation, or does the Senate have to impose it? How does resignation differ from conviction in regards to subsequent civil and criminal prosecution?