Interrogatories are a discovery tool (among many) used in lawsuits in New York courts. In sum, these are written questions seeking specific information.The purpose of your interrogatories should be to uncover evidence for your case. 1. Except as otherwise provided herein, after commencement of an action, any party may serve upon any other party written interrogatories. Use this "At A Glance Guide" to learn the statewide rules of civil procedure applicable to responding to interrogatories in New York Supreme Court. Further changes in the new discovery procedures effective January 1, 1973, find that interrogatories now may be served with the complaint. Your legal team will ask you to fill out a detailed questionnaire.