Defendant's Interrogatories in Patent Litigation
(Alleged Infringer to Patent Owner)

Summary

This template is a Defendant's Interrogatories in Patent Litigation for use by an accused infringer as a starting point in preparing interrogatories for service on a patent owner. The template includes interrogatories seeking information relevant to issues such as claim construction, infringement, the effective filing date of the asserted patent claims, prior art, invalidity, and damages. The template also includes practical guidance and drafting notes. Use interrogatories to request information not readily obtainable from document requests, depositions, initial disclosures under Fed. R. Civ. P. 26(a), or any mandatory disclosures of claim construction and infringement/validity contentions under local patent rules. It is important to tailor your interrogatories to the facts and issues in your case, taking into account Rule 26(b)'s proportionality factors. Also consult local court rules and local patent rules for any restrictions or requirements for interrogatories. (See, e.g., Southern District of New York L. Civ. R. 33.3 restricting use of interrogatories and allowing contention interrogatories only at the conclusion of other discovery). Answers to interrogatories may be used at trial to the extent permitted by the Federal Rules of Evidence. Fed. R. Civ. P. 33(c). You may serve interrogatories after your Rule 26(f) conference has been held. See Fed. R. Civ. P. 26(d)(1). Interrogatories served later in the case should be served at least 30 days before the close of discovery. Unless otherwise stipulated or ordered by the court, Rule 33 limits the number of interrogatories to 25. The court may impose a different limit in a case management order or local rules. Discrete subparts of an interrogatory count toward the 25 interrogatory limit. See Fed. R. Civ. P. 33(a)(1). Courts vary in how they define a discrete subpart, so check local case law on this issue before formulating your interrogatories. For a discussion of the case law, see 7-33 Moore's Federal Practice - Civil § 33.30. In general, courts treat subparts as part of a single interrogatory where they are subsumed in or necessarily related to the primary question. See, e.g., Medigus Ltd. v. Endochoice, Inc., 2016 U.S. Dist. LEXIS 156752, at *3 (D. Del. July 19, 2016). Consider using interrogatories to obtain: •The opposing party's contentions on claim construction, infringement, and validity (if there is no case management order or local patent rules otherwise providing for such disclosure) •Information such as product numbers, the numbers of related patents and applications, technical or statistical data •The identity of knowledgeable persons (whom you may wish to depose) •The identity of important documents and other evidence Avoid broad, general language that may elicit objections or useless responses. The most effective interrogatories are precise, succinct, and unambiguous, leaving no room to avoid answering the question. To gauge the effectiveness of an interrogatory, consider how you would respond if you were on the receiving end. Craft interrogatories seeking identification of documents or facts carefully to avoid an objection that the interrogatory seeks counsel's selection of documents or facts, which may be protected as attorney work product. Courts have reached different conclusions on this issue. See, e.g., American Nat'l Red Cross v. Travelers Indem. Co., 896 F. Supp. 8, 13–14 (D.D.C. 1995); SEC v. Collins & Aikman Corp., 256 F.R.D. 403, 410 (S.D.N.Y. 2009); Bianchi v. Green, 2021 U.S. Dist. LEXIS 247516, at *15 (N.D.N.Y. Aug. 10, 2021). For a discussion of the use of interrogatories in patent litigation, see Horwitz on Patent Litigation § 5.04[2]. For more general information on the use of interrogatories in federal litigation, see Interrogatories: Drafting and Serving Interrogatories (Federal).