ยง  420.  Form  of  objection or denial. If the defendant object to the
  sufficiency of the impeachment, the objection must be  in  writing,  but
  need  not  be  in  any specific form; it being sufficient, if it present
  intelligibly the grounds of the objection. If he deny the truth  of  the
  impeachment,  the  denial  may  be  oral,  and without oath, and must be
  entered upon the minutes.
Structure New York Laws
Article 13-A - Judicial Proceedings for the Removal of Public Officers by Impeachment
415 - Impeachment to Be Delivered to President of the Senate.
416 - Copy of Impeachment Served on Defendant.
418 - Proceedings, if Defendant Does Not Appear.
419 - Defendant May Object to Sufficiency Of, or Deny Impeachment.
420 - Form of Objection or Denial.
422 - Two-Thirds Necessary to Conviction.
423 - Judgment on Conviction, How Pronounced.
426 - Officer, When Impeached, Disqualified to Act Until Acquitted.
427 - Presiding Officer, When President of the Senate Is Impeached.