With the completion on Wednesday of the engrossment ceremony and the ceremonial delivery by a delegation from the House of Representatives to the Senate of two articles of impeachment against President Donald Trump, the next stage of an uncommonly formalistic process arrives at midday Thursday: the administration to members of the Senate, as jurors in the impeachment trial, of an oath of impartiality.

Its wording, per rules adopted in 1868, can be expected to follow this format:

‘I solemnly swear (or affirm, as the case may be,) that in all things appertaining to the trial of the impeachment of Donald J. Trump, now pending, I will do impartial justice according to the Constitution and laws: so help me God.’

Opening statements and arguments in the Senate, presided over by Chief Justice John Roberts, are expected to begin Tuesday, following the Martin Luther King holiday.

Roberts is to be sworn in before the senators are.

“Nothing in the rules the Senate agreed to in the 1980s,” writes Amber Phillips of the Washington Post, “says the chief justice or anyone else can punish senators for not being impartial.”