(CNN)Let's call it the Pelosi Pause. There are no written rules governing the timetable for delivery of the House decision impeaching Donald Trump to the Senate, only custom. But then there were no written rules governing the timetable for a Senate decision on Barack Obama's nomination of Merrick Garland, only custom. If Speaker Nancy Pelosi follows Senator Mitch McConnell's playbook, Donald Trump will never stand trial in the Senate. Joseph Ellis Joseph Ellis From a Democratic perspective that outcome would be preferable to a show trial, where the conclusion is not just foreordained, but announced beforehand by the Majority Leader...