N.Y. Jud. Law § 246

§ 246. Oath to members of the court. At the time and place appointed,\nand before the court proceeds to act upon the impeachment, the clerk\nmust administer to the presiding judge, and the presiding judge to each\nof the members of the court then present, an oath or affirmation truly\nand impartially to try and determine the impeachment; and no member of\nthe court can act or vote upon the impeachment, or any question arising\nthereon, without having taken this oath or affirmation.\n