WASHINGTON (AP) — Chief Justice John Roberts was sworn in Thursday to preside over President Donald Trump’s impeachment trial, then immediately administered the oath to the full Senate to ensure “impartial justice” as jurors for only the third such proceeding in American. history. Roberts made the short trip across the street from the Supreme Court before being ushered to the Senate chamber. "Will all senators now stand, and remain standing, and raise their right hand," Roberts said. “Do you solemnly swear that in all things appertaining to the trial of the impeachment of Donald John Trump, president of the United States, now pending, you will do impartial justice according to the Constitution and laws, so help you God?” The senators, at their desks, responded and then were called up to sign the oath book The Constitution mandates the chief justice serve as the presiding officer.