N.Y. Second Class Cities Law § 201

§ 201. Duties of the corporation counsel. The corporation counsel\nshall be and act as the legal adviser of the common council and of the\nseveral officers, boards and departments of the city. He shall appear\nfor and protect the rights and interests of the city in all actions,\nsuits and proceedings brought by or against it or any city officer,\nboard or department, including the commissioner of charities in bastardy\nproceedings; and such officer, board or department shall not employ\nother counsel. The corporation counsel may, however, with the written\nconsent of the mayor, employ counsel, at such compensation as may be\napproved by the board of estimate and apportionment, to assist him in\nthe argument and conduct of important cases or proceedings in which the\ncity or any officer, board or department thereof is interested or a\nparty.\n