involved, at the appellate and of any effort to enforce subpoenas. >> the chief justice, if there is a trial, serves as the judge. >> the constitution says and impeachment of the president, the chief justice is to be the presiding officer. to a large extent, the chief justice does not do very much in the proceedings. he convenes and makes provisional rulings, but in the end, the senate itself decides what the ruling will be and what evidence will be permitted. if there is an objection to the evidence, a chief justice might make a preliminary ruling but if the other side doesn't like it they put it to the vote of the full senate. >> steve bannon is telling the new york post he expects the house to convene and impeachment vote in the next six weeks. if that were to happen, when could we see a trial in the senate? >> there are some questions about whether or not the senate is obliged to have a trial at all, that has been discussed a lot in the media. i think the answer is the constitution certainly implies an obligation on the part of the senate to hold a trial. it is remarkably terse o