Under amended Supreme Court Rule 213(j) (eff. Any party serving discovery shall file a certificate of service of discovery document.{Amended April 22, 2013}. A party may direct written interrogatories to any other party. A copy of the interrogatories shall be served on all other parties entitled to notice. Any party serving discovery shall file a. Instead, a party serving discovery shall file a certificate of service of discovery document. This Note addresses interrogatory basics, such as drafting definitions, instructions, and specific interrogatories, and serving interrogatories. A party can only send 30 interrogatories. However, this number can be increased if the other party agrees or the court allows more.