An interrogatory is a written question one party serves on another, answered in writing and under oath under Federal Rule of Civil Procedure 33. Because the answer is verified under oath, it is a commitment, not a casual statement — it can be used to impeach a witness, as an evidentiary admission, or as leverage at summary judgment. Responding rewards discipline and punishes carelessness. This checklist gives you the sequence.

For the full treatment, see mastering interrogatories. It pairs with the responding to requests for production checklist and the responding to requests for admission checklist.

Phase 1: Calendar and check the rules

  • Calendar the deadline: 30 days from service (Rule 33(b)(2)), adjusted for service method and any local-rule or stipulated extension. Missing it risks waiver of objections — including, in many courts, privilege (Rule 33(b)(4)).
  • Read the district's local civil rules, the assigned judge's individual rules, and any case-specific discovery order — they routinely modify Rule 33 (uniform definitions, formatting, restatement of each question before the answer, different limits, contention-interrogatory timing).

Why this matters. If interrogatories do not conform to the applicable rules, a court may rule the responding party need not answer them — but only if you spot the issue and raise it. A late objection is presumptively waived absent good cause.

Phase 2: Count the interrogatories

  • Count the interrogatories, including all discrete subparts, against the presumptive limit of 25 per opposing party (Rule 33(a)(1)).
  • Apply the discrete-subparts test: a subpart that merely elaborates the primary question (the who/when/how/what of a communication) counts as part of one; a subpart that opens a genuinely distinct line of inquiry counts as a separate interrogatory.
  • If the set exceeds 25, object to the excess after a good-faith meet-and-confer about which subparts count.

Why this matters. The cap is per party and cumulative across the action; a party that blows through it without permission generally cannot compel answers to the excess. The test draws on the 1993 Advisory Committee Note and cases like Superior Communications v. Earhugger, 257 F.R.D. 215 (C.D. Cal. 2009).

Phase 3: Conduct the reasonable inquiry

  • Interview the people who know and search the company's records — the duty is to answer using all nonprivileged responsive information available to the party, its attorneys, agents, or representatives, or obtainable after a reasonable investigation.
  • For an entity, designate an officer or agent who collects the information and may verify on information and belief gathered from the organization.
  • Document the search, so a later "after reasonable inquiry, [party] is unable to admit or deny" or "unable to locate" answer is credible.

Why this matters. A designated representative who answers only from personal recollection has failed the duty (Shepherd v. American Broadcasting Cos., 62 F.3d 1469 (D.C. Cir. 1995)). A bare "unknown" invites a motion to compel; a response describing the efforts made satisfies Rule 33.

Phase 4: Draft objections and answers

  • State each objection with specificity (Rule 33(b)(4)), tied to the particular question and explaining the basis; abandon generic "overly broad, unduly burdensome, vague" boilerplate and the deleted "reasonably calculated" language.
  • State whether any responsive material is withheld on the basis of each objection (read across from the 2015 Rule 34 amendment).
  • Where part of an interrogatory is objectionable, object to that part, specify which, and answer the rest.
  • Support a proportionality objection with concrete figures (custodians, document volume, review hours, dollar estimates) — the responding party bears the initial burden of showing disproportionality.
  • For a contention interrogatory served early, consider objecting that it is premature under Rule 33(a)(2) and answering at the close of fact discovery (check local rules; some courts require a present answer subject to supplementation).
  • For privilege, object specifically, answer the underlying facts (privilege protects communications, not facts), and provide a privilege log under Rule 26(b)(5).

Why this matters. Courts increasingly disregard, strike, or sanction boilerplate objections (Heller v. City of Dallas, 303 F.R.D. 466 (N.D. Tex. 2014)). A burden objection unsupported by real numbers will be overruled (State Farm v. Pointe Physical Therapy, 255 F. Supp. 3d 700 (E.D. Mich. 2017)).

Phase 5: Consider Rule 33(d), verify, and supplement

  • Where the answer can be derived from business records and the burden is substantially the same for either party, expressly elect Rule 33(d) and specify the records with particularity, with an index if voluminous — do not silently produce documents or point to "documents already produced."
  • Verify under oath: the party (or designated corporate representative) signs the answers; counsel signs the objections and certifies under Rule 26(g). Use a 28 U.S.C. § 1746 declaration (no notary required).
  • Diary the continuing duty to supplement (Rule 26(e)); failure can preclude the omitted information or witness at trial under Rule 37(c)(1).
  • Confer in good faith before any motion; document dates, participants, issues, and agreements.

Why this matters. A defective verification can render the answers unsworn and expose the party to a motion to compel. Rule 33(d) is a genuine convenience when the burden is equal and the records are specified, and a trap when invoked loosely (VeroBlue Farms USA v. Wulf, 2021 WL 5176839 (N.D. Tex. 2021)). The motion-to-compel cost-shifting presumption of Rule 37(a)(5) runs both ways — confer seriously and assert only defensible objections.

Phase 6: Use interrogatories as offense and defense

Responding well is half the discipline; the other half is choosing what to ask and when, because the same twenty-five questions can be spent wisely or wasted.

  • Do not burn interrogatories on information Rule 26(a)(1) already requires the opponent to disclose without a request (witnesses it will rely on, documents it will use, damages computations). Reach beyond the automatic disclosures — for adverse witnesses and unfavorable documents the opponent would never volunteer, and for the assumptions behind a bare damages number.
  • Serve a first set early to identify witnesses and locate documents; hold several questions back for targeted contention interrogatories late in the case, after documents and depositions have exposed the opponent's theory.
  • Use the right device for the job: a request for admission (no numerical cap) to establish that a discrete fact is undisputed; a Rule 34 request to get documents (an interrogatory may be answered with documents under Rule 33(d) but cannot serve as a document request — Terracon Consultants v. Drash, 2013 WL 1633572 (D. Kan. 2013)); a deposition to probe credibility and follow a thread in real time.
  • Remember interrogatories run only between parties; to get written facts from a nonparty, use an oral deposition under Rule 30 (with a subpoena) or, rarely, a deposition by written question under Rule 31.

Why this matters. A precisely worded contention interrogatory forces the opponent to commit its factual basis for each claim or defense, narrowing the issues and exposing theories with no evidentiary support — fertile ground for summary judgment. Because the answer is verified, a witness who later testifies inconsistently can be confronted with it, and an answer conceding an element can be quoted in a dispositive motion (Rule 33(c)). On defense, answer fully and accurately — shading an unfavorable fact is unethical and, when exposed, devastating to credibility — but answer the question asked, not a broader one. And calibrate aggressiveness to the case: discovery is a long game played with the same opposing counsel before the same judge, and reasonable cooperation earns the court's trust when a genuinely important dispute arises.

Phase 7: When the system breaks down — motions and protective orders

  • Before any motion to compel, confer in good faith (Rule 37(a)(1)); many districts require a real conversation, not an exchange of form letters, and a perfunctory certification can sink an otherwise meritorious motion.
  • Recognize that an evasive or incomplete answer is treated as a failure to answer (Rule 37(a)(4)) — so a non-answer dressed up as an answer is fair game for a motion to compel.
  • Know the burden allocation: the movant generally shows relevance and proportionality, but when you assert privilege or a specific protective objection, the burden shifts to you to establish it — privilege is never presumed.
  • Where sensitive but discoverable material is at stake (trade secrets, customer lists, pricing, personal financial data), seek a protective order under Rule 26(c) that limits use and dissemination rather than flatly refusing to answer.
  • Understand the escalation: if a court orders answers and the party defies the order, Rule 37(b)(2) authorizes deeming facts established, barring claims or evidence, striking pleadings, dismissal, default, or contempt; Rule 37(d) sanctions a complete failure to answer without a prior order; and Rule 26(g) independently sanctions an unreasonable inquiry or improper certification.

Why this matters. The meet-and-confer is where overbreadth becomes a narrowed time frame, a burden objection becomes a phased production, and a vague term gets defined. The cost-shifting presumption of Rule 37(a)(5) is symmetric — it punishes the obstructive responder and the requester who moves without conferring or who loses — which is a strong incentive to assert only objections you would actually argue to the judge.

Common mistakes

  • A block of "General Objections" substituting for specific, question-by-question objections.
  • Answering only from the verifying person's personal recollection instead of the entity's collected knowledge.
  • Invoking Rule 33(d) without electing it expressly or specifying records with particularity.
  • Counsel verifying the answers in the client's place (counsel signs objections; the party verifies answers).
  • Forgetting to supplement, risking exclusion of your best evidence at trial.

Primary authority

  • Fed. R. Civ. P. 33 (mechanics, 25-question limit, discrete subparts, contention interrogatories, Rule 33(d)); 26(b)(1) (scope and proportionality); 26(b)(5) (privilege log); 26(e) (supplementation); 26(g) (certification); 37(a) (motion to compel/cost-shifting) and 37(c)(1) (preclusion).
  • Key cases: Heller v. City of Dallas, 303 F.R.D. 466 (N.D. Tex. 2014); Superior Communications v. Earhugger, 257 F.R.D. 215 (C.D. Cal. 2009); State Farm v. Pointe Physical Therapy, 255 F. Supp. 3d 700 (E.D. Mich. 2017); Shepherd v. ABC, 62 F.3d 1469 (D.C. Cir. 1995); VeroBlue Farms v. Wulf, 2021 WL 5176839 (N.D. Tex. 2021).

Related resources

This checklist is provided for general informational purposes only and does not constitute legal advice. Discovery rules vary by jurisdiction and change over time. Consult qualified counsel licensed in your jurisdiction before acting.