Trump impeachment trial opens with "impartial justice" oath

• They stood as a group while Chief Justice John Roberts was sworn in, and they remained standing as he swore them in.
• Reporters were forced back to paper notebooks, since they aren't allowed to bring any technology such as phones or laptops into the Senate chamber.

Between the lines: For the next few weeks, the Senate will be an extremely different institution — with consequences that extend to the Democratic presidential primaries.

• Starting at 1 p.m. ET on Tuesday, Sens. Bernie Sanders, Elizabeth Warren and Amy Klobuchar will be busy on Capitol Hill, with Joe Biden and Pete Buttigieg free to barnstorm Iowa.
• Sanders would "rather be in Iowa today," he told Politico. "There’s a caucus there in two-and-a-half weeks. I’d rather be in New Hampshire and Nevada. But I swore a constitutional oath as a U.S. senator to do my job.”

What's next:

• House briefs due 5 p.m. Saturday.
• Trump's briefs due 12 p.m. Monday.
• House reply due 12 p.m. Tuesday.
• Opening arguments begin 1 p.m. Tuesday.

Go deeper: Watch Chief Justice John Roberts swear in senators