The Senate impeachment trial of President Donald Trump began Tuesday with a fierce debate over the rules that Senate Majority Leader Mitch McConnell put forth for the proceedings.

Key sticking points included the questions of whether any witnesses will be called and whether new evidence can be introduced. Republicans maintained that only information learned during the House proceedings should count and Democrats argued it is the Senate’s duty to hear all available evidence.

Nancy Gertner, a retired federal judge and senior lecturer at Harvard Law School; and Renee Landers, Suffolk Law Professor and constitutional law expert joined Jim Braude Tuesday on Greater Boston to discuss the first day of the president's trial in the Senate.