“An interrogatory is a written question asked by one party to another party, who must answer under oath and in writing. The answer may be used in evidence against the answering party. The Judicial Council has published ‘form interrogatories’ for optional use in a variety of cases. Parties may draft their own interrogatories, which are termed ‘special interrogatories.’ Special interrogatories are subject to the ‘Rule of 35’; form interrogatories are not.”
“Interrogatories may be sent to “any other party” to the action. Interrogatories cannot be served on nonparty witnesses. There is no requirement that the party to whom interrogatories are sent be adverse to the propounding party. Thus, for example, plaintiff can, if it chooses, serve interrogatories on a coplaintiff; and defendant can serve interrogatories on a codefendant. The response is due within 30 days from the date the interrogatories were served (extended for service by mail, overnight delivery, fax or electronically).”
“If a party to whom interrogatories are directed either fails to respond at all, or responds with objections or incomplete answers, the propounding party’s remedy is to seek a court order compelling answers (or further answers) to the interrogatories.”
[California Practice Guide: Civil Procedure Before Trial [citations to primary sources omitted]]
