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. For example, only 25 interrogatories (including subparts) may be served (Comm'l Div. In many civil actions, before the case is resolved there takes place a process known as pretrial discovery. This summary describes the process. Complete 10 days after the filing. Unless otherwise specified in the preliminary conference order, only 25 interrogatories may be served in any action, including consolidated actions.