Laurence Tribe is a professor of constitutional law at Harvard University. He is the author of "To End a Presidency: The Power of Impeachment".
Professor Tribe offers a warning--now fulfilled--that the final Mueller report about Trump and Russia would not save America because the special counsel's mandates were too narrow.
And Laurence Tribe ponders the frightening question: What if Donald Trump is defeated in 2020 and he refuses to leave the presidency?