N.Y. JUD Law § 493

§ 493. Attorneys forbidden to defend criminal prosecutions carried on\nby their partners, or formerly by themselves. An attorney, who directly\nor indirectly advises in relation to, or aids or promotes the defense of\nany action or proceeding in any court, the prosecution of which is\ncarried on, aided or promoted by a person as district attorney or other\npublic prosecutor, with whom such attorney is directly or indirectly\nconnected as a partner; or who, having himself prosecuted or in any\nmanner aided or promoted any action of proceeding in any court, as\ndistrict attorney or other public prosecutor, afterwards directly or\nindirectly advises in relation to, or takes any part in, the defense\nthereof, as attorney or otherwise; or who takes or receives any valuable\nconsideration from or on behalf of any defendant in any such action,\nupon any understanding or agreement whatever, express or implied, having\nrelation to the defense thereof, is guilty of a misdemeanor.\n