The Senate formally opened the impeachment trial of President Trump on Thursday, bracing for a deeply divisive debate over his fate as senators swore to deliver “impartial justice” and installed Chief Justice John G. Roberts Jr. to preside over the proceeding.

In a somber ceremony that initiated only the third presidential impeachment trial in the nation’s history, Chief Justice Roberts vowed to act “according to the Constitution and the laws.” He then administered the same, 222-year-old oath of impartiality to the senators, setting in motion the final stage of a process that has roiled Congress and could shape the outcome of the 2020 elections, along with Mr. Trump’s legacy.

Even as the ritual unfolded in the chamber, with senators signing their names one by one in an oath book near the marble Senate rostrum, new evidence was emerging about Mr. Trump’s pressure campaign on Ukraine that is at the heart of the charges against him.

A trove of texts, voice mail messages, calendar entries and other records handed over by Lev Parnas, an associate of the president’s personal lawyer Rudolph W. Giuliani, offered additional detail about the scheme. And the Government Accountability Office, a nonpartisan federal watchdog, found that Mr. Trump’s decision to withhold military aid from Ukraine, which the House charges was part of his pressure campaign, was a violation of the law.

Further Reading: https://www.nytimes.com/2020/01/16/us/politics/trump-impeachment.html