New York Consolidated Laws, Criminal Procedure Law - CPL § 60.40 Rules of evidence;  proof of previous conviction;  when allowed

1. If in the course of a criminal proceeding, any witness, including a defendant, is properly asked whether he was previously convicted of a specified offense and answers in the negative or in an equivocal manner, the party adverse to the one who called him may independently prove such conviction.  If in response to proper inquiry whether he has ever been convicted of any offense the witness answers in the negative or in an equivocal manner, the adverse party may independently prove any previous conviction of the witness.

2. If a defendant in a criminal proceeding, through the testimony of a witness called by him, offers evidence of his good character, the people may independently prove any previous conviction of the defendant for an offense the commission of which would tend to negate any character trait or quality attributed to the defendant in such witness' testimony.

3. Subject to the limitations prescribed in section 200.60, the people may prove that a defendant has been previously convicted of an offense when the fact of such previous conviction constitutes an element of the offense charged, or proof thereof is otherwise essential to the establishment of a legally sufficient case.