N.Y. County Law § 703

§ 703. Employment of counsel. With the written approval of the county\njudge of a county in which an indictment has been found for a capital or\nother crime which presents unusual difficulty upon the trial thereof,\nthe district attorney may employ counsel to assist him upon such trial.\nSuch approval shall be filed in the office of the county clerk. The\nboard of supervisors shall audit as other county charges a reasonable\ncompensation and the necessary expenses of such counsel as certified by\nthe presiding judge or justice.\n