Interrogatories are a discovery tool (among many) used in lawsuits in New York courts. In sum, these are written questions seeking specific information.In many civil actions, before the case is resolved there takes place a process known as pretrial discovery. This summary describes the process. Service of interrogatories. It helps if you fill in the top part of the form with the case and court information. 1. Except as otherwise provided herein, after commencement of an action, any party may serve upon any other party written interrogatories. The U.S. Postal Service that same day in the ordinary course of business.