What Is an Interrogatory? Answers, Objections, and Limits

An interrogatory is a written question one party in a civil lawsuit sends to another party, who must answer it in writing and under oath. In federal court, Federal Rule of Civil Procedure 33 governs the process: each party may serve up to 25 interrogatories, and the recipient has 30 days to respond.¹ It’s one of the main tools of pretrial discovery, the phase where both sides exchange facts so the trial itself can focus on what’s actually in dispute.

What Interrogatories Are For

Interrogatories pin down facts the other side knows but hasn’t shared. A plaintiff might use them to learn what insurance coverage a defendant carries. A defendant might use them to identify every medical provider the plaintiff saw after an accident. Because the recipient gets 30 days to put together a response, interrogatories are especially useful when the answer takes digging — through financial records, business files, medical histories — rather than something a witness could answer off the top of their head in a deposition.

One boundary matters up front: interrogatories can only be sent to parties in the lawsuit.¹ If you need information from a non-party witness or an outside company, you use a subpoena or a deposition instead.

Common Kinds of Interrogatories

Not every interrogatory asks the same kind of question.

Identification questions ask you to name people, documents, or things — for example, every witness to an accident or every document that supports a claim. They tell each side where to look next.
Fact questions ask for your version of events: what you did on the day of the accident, what medical expenses you’ve paid, how a contract was negotiated. The point is to lock down the facts in writing under oath.
Contention questions ask a party to explain the legal or factual basis for a claim or defense. Rule 33 specifically permits questions calling for “an opinion or contention that relates to fact or the application of law to fact,” though a court can push the deadline for answering these to later in the case, once more discovery is done.¹

Many state courts also publish pre-approved “form interrogatories” covering standard topics like insurance, damages, and witness identification. They save time because the wording has already been vetted. When the form questions don’t fit, parties draft custom interrogatories tailored to the case.

How You Answer Them

Each interrogatory is answered separately, fully, in writing, and under oath.¹ That generally means pulling records — pay stubs, bills, calendars, emails, contracts — to make sure the answers are accurate. Because the response is sworn, a false answer can be treated as perjury and used against you at trial.

The party answering signs the responses. The attorney signs only the objections.¹ That split puts personal responsibility for the facts on the party. For an organization — a corporation or government agency — any officer or agent with access to the information can sign on its behalf.

Answering From Business Records

When the answer sits inside a stack of business records, Rule 33(d) lets you give the other side access to the records instead of composing a narrative answer, so long as two things are true: the answer really can be found by reviewing those records, and the burden of finding it would be about the same for either side. You still have to identify the specific records clearly enough that the other party can locate the information without a hunt.¹ This option shows up most in complex commercial cases, where the underlying data is voluminous and already organized.

“Information and Belief”

You won’t always have firsthand knowledge of every fact a question touches. In that situation, you can qualify an answer by stating it’s based on “information and belief” rather than personal knowledge — appropriate when the facts come from records or secondhand sources rather than something you personally observed. The duty to investigate still applies. Claiming ignorance about facts you could easily have checked doesn’t protect you, and courts treat willful ignorance as the equivalent of actual knowledge.

When You Can Object

You don’t have to answer every question. If an interrogatory is irrelevant, overly broad, seeks privileged information, or looks designed to harass rather than gather facts, you can object. Boilerplate won’t do the job. Writing “vague, overly broad, and unduly burdensome” with no explanation is likely to be ignored and can draw sanctions. The objection has to say specifically what’s wrong with the question and why.

Typical grounds include:

Privilege — the question seeks attorney-client communications or work product prepared in anticipation of litigation.
Irrelevance — the information has no connection to any claim or defense in the case.
Disproportionate burden — the work of answering outweighs the information’s value, given the stakes and the issues.
Vagueness — the question is so unclear you can’t tell what’s being asked. Even then, you’re expected to try to clarify before objecting on this ground.

Timing is strict. Under Rule 33(b)(4), any objection you don’t raise within the 30-day response window is waived unless the court excuses the delay for good cause.¹ Miss the deadline and you may be forced to answer questions you had every right to refuse.

The 25-Question Cap and the Scope Rule

Rule 33 caps interrogatories at 25 per party, including all discrete subparts.¹ A single numbered question that asks for every witness’s name, address, phone number, and relationship to the events counts as multiple interrogatories, not one. Courts watch for drafting that tries to pack dozens of questions into a handful of numbered items. If you genuinely need more than 25, you can ask the court for leave, but you’ll need to show the complexity of the case justifies it.

State courts set their own limits, and they vary. Some allow 30, some cap at 15, some rely on judges to police abuse without a fixed number. Don’t assume the federal number applies in state court.

Every interrogatory also has to fit within the general scope of discovery. Under Rule 26(b)(1), the question must seek information relevant to a party’s claim or defense and proportional to the needs of the case.² Courts weigh the amount at stake, each side’s access to the information, and whether the cost of answering outweighs the likely benefit. Information doesn’t have to be admissible at trial to be discoverable; it just has to be relevant and proportional.

If the Other Side Won’t Answer

If 30 days pass with no response, or the answers come back evasive or incomplete, the party who sent the interrogatories can file a motion to compel. Before going to the judge, Rule 37 requires certifying a good-faith effort to resolve the dispute without court intervention.³ Judges don’t want to referee fights that a phone call could have settled.

If the motion is granted, the losing side generally pays the winner’s reasonable expenses, including attorney’s fees, which can run into real money depending on how much work the motion took.³ If a party then defies a court order compelling answers, the consequences get much worse. The court can:

Treat the disputed facts as established against the non-compliant party
Bar that party from presenting certain evidence or raising certain defenses
Strike pleadings in whole or in part
Dismiss the case or enter default judgment
Hold the party in contempt

Courts use these remedies.³ Discovery abuse is one of the quickest ways to lose a case you might otherwise have won.

Protective Orders

The mirror image of the motion to compel is the protective order. If you believe interrogatories are being used to harass you, drive up costs, or dig into trade secrets, you can ask the court for protection before answering. Under Rule 26(c), the court can limit or block discovery for good cause to shield a party from annoyance, embarrassment, oppression, or disproportionate expense.² A protective order can narrow the questions, limit who sees the answers, require that sensitive material be produced only under a confidentiality agreement, or forbid certain lines of inquiry outright. As with motions to compel, judges expect the parties to meet and confer first.

The Duty to Supplement

Your obligation doesn’t end when you send your answers in. Under Rule 26(e), if you later learn that an interrogatory response was incomplete or wrong, you have to supplement or correct it in a timely manner.² That duty runs through trial. There’s no fixed deadline, but courts expect updates as soon as you know an earlier answer needs fixing. The penalty for ignoring it is harsh: the court can exclude information you should have disclosed. A late-discovered witness you never disclosed might be barred from testifying; documents you failed to identify could be kept out of evidence. The way out is showing either that the failure was harmless or that you had substantial justification.

How Interrogatory Answers Show Up at Trial

Interrogatories aren’t just a pretrial exercise. Under Rule 33(c), an answer can be used at trial to the extent the rules of evidence allow.¹ In practice, that means the opposing party can read your answers into evidence against you. If you said one thing in a response and then testify differently on the stand, the inconsistency will come up. Because the answers were sworn, they carry weight with judges and juries. Treating interrogatories as a throwaway chore is where most parties get themselves into trouble.

1
Legal Information Institute. Federal Rules of Civil Procedure Rule 33 – Interrogatories to Parties
2
Legal Information Institute. Federal Rules of Civil Procedure Rule 26 – Duty to Disclose; General Provisions Governing Discovery
3
Legal Information Institute. Federal Rules of Civil Procedure Rule 37 – Failure to Make Disclosures or to Cooperate in Discovery; Sanctions