N.Y. Fam. Ct. Act § 344.3
When, in connection with a defense of mental disease or defect, a psychiatrist or licensed psychologist who has examined the respondent testifies at the fact-finding hearing concerning the respondent's mental condition at the time of the conduct charged to constitute a crime, he must be permitted to make a statement as to the nature of the examination, the diagnosis of the mental condition of the respondent and his opinion as to the extent, if any, to which the capacity of the respondent to know or appreciate the nature and consequences of such conduct, or its wrongfulness, was impaired as a result of mental disease or defect at that time. The psychiatrist must be permitted to make any explanation reasonably serving to clarify his diagnosis and opinion, and may be cross-examined as to any matter bearing on his competency or credibility or the validity of his diagnosis or opinion.
N.Y. Family Court Law § 344.3