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. 1. Except as otherwise provided herein, after commencement of an action, any party may serve upon any other party written interrogatories. In many civil actions, before the case is resolved there takes place a process known as pretrial discovery. This summary describes the process. Any party may serve written interrogatories on any other party. This document outlines class notes focusing on subpoenas, discovery tools, and interrogatories within civil procedure.