Delivering legal papers is called "service of process". The law says that legal papers have to be "served" (delivered) the right way.To find Affidavits of Service go to Forms, visit a Court Help Center or ask the Court for one, most Courts will have this. Interrogatories are a discovery tool (among many) used in lawsuits in New York courts. In sum, these are written questions seeking specific information. Service of interrogatories. After commencement of an action, any party may serve written interrogatories upon any other party. These rules are the Local Rules of Civil Procedure for the United States District Court for the Western District of New York. 1. Except as otherwise provided herein, after commencement of an action, any party may serve upon any other party written interrogatories. See Siegel, New York Practice § 107.