Illinois Interrogatories: Limits, 28-Day Deadline, and Objections

Illinois interrogatories are governed by Illinois Supreme Court Rule 213, which lets a party in a civil lawsuit send up to 30 written questions to any opposing party and requires each question to be answered in writing, under oath, within 28 days.¹ The rules also carry real teeth: witnesses and opinions that were not disclosed through interrogatory answers can be barred at trial, and a party who ignores a court order to answer can face default judgment.

What Interrogatories Are For

An interrogatory is a written question one party sends to another, demanding a written answer signed under oath. Unlike a deposition, where you question one person about what they personally recall, an interrogatory answer must draw on everything the party and their organization know collectively. A party cannot dodge by saying “I don’t know” if the information sits somewhere in their files or with their employees.

That is why interrogatories usually come first in discovery. They pin down the basics — who the witnesses are, what documents exist, what legal theories the other side will rely on — and the answers set up the more expensive discovery that follows. Once an interrogatory answer confirms that a key contract exists, you can demand a copy through a document request under Illinois Supreme Court Rule 214.² Once an answer identifies a specific employee as a witness, you can schedule their deposition.

How Many Questions You Can Send

Rule 213 caps each party at 30 interrogatories to any single opposing party, and subparts count. You cannot nest multiple questions inside one numbered item to stretch the limit.¹ The parties can agree to allow more, or a party can move the court for permission, attaching the proposed additional questions and explaining why the case warrants them.

Illinois also recognizes “form interrogatories,” pre-approved question sets covering standard topics. A form interrogatory counts as one question toward the 30 regardless of how many internal subparts it contains.³ Form interrogatories can be mixed with custom questions, but the combined total still cannot exceed 30 without agreement or a court order.

The 28-Day Deadline and What an Answer Must Include

The responding party has 28 days from the date of service to provide a sworn answer or a valid objection to each interrogatory.¹ Each answer must restate the full text of the interrogatory immediately before it, so anyone reading the response can follow the sequence without a second document.

Answers are given under oath. The signing party swears the responses are truthful, using an attestation clause of the kind the Illinois courts publish, typically with notarization.³ That oath matters at trial: because the answers are sworn, they can be used to impeach a party who later tells a different story.

The duty to answer requires a reasonable investigation. When the responding party is a corporation, partnership, or similar organization, an officer or agent must answer on the organization’s behalf and must provide whatever information is available to the organization as a whole.¹ The complete verified response, with all answers and objections, must be served on the propounding party and every other party entitled to notice within the 28-day window.

What You Can Ask About

The scope of discovery in Illinois is broad. Under Illinois Supreme Court Rule 201, a party can seek any information relevant to the subject matter of the lawsuit, including the existence and location of documents, the identity of people with knowledge of relevant facts, and details about the other side’s claims or defenses.⁴ Information does not have to be admissible at trial to be discoverable. It only has to be relevant to an issue in the case.

Two categories are off-limits. Privileged communications, most commonly between a party and their attorney, cannot be discovered. Materials prepared by a party or their attorney in anticipation of litigation are also protected when they contain the attorney’s mental impressions, analysis, or litigation strategy.⁴ The identity and opinions of a consultant hired to help prepare for trial who will not testify are discoverable only if the requesting party shows exceptional circumstances making it impractical to get the same information another way.

Rule 201 also lets a court issue a protective order to prevent unreasonable expense, embarrassment, or burden. The court weighs the likely benefit of the discovery against its burden, considering the amount at stake, each side’s resources, and how important the requested information is to resolving the dispute. Rule 213 itself tells drafters to keep interrogatories focused on the case and to avoid unnecessary detail or expense for the answering party.¹

Objecting to a Question

If a question is objectionable, the responding party must state the specific legal reason. A blanket “objection” with no explanation will not hold up. Common grounds include attorney-client privilege, work product protection, undue burden, and vagueness. An objection to one part of a question does not excuse the party from answering the rest: if a question asks for both a date and a privileged legal analysis, the date still has to be provided. Evasive or incomplete answers are treated the same as a failure to answer, which opens the door to a motion to compel.

Producing Documents Instead of Writing an Answer

When the answer to a question can be found in documents the responding party already has, Rule 213 allows the party to produce those documents rather than writing out a narrative explanation.¹ The production must comply with Rule 214’s requirements for document discovery.² Financial records and medical bills are typical examples of situations where the documents speak more clearly than a summary.

Witness Disclosure Under Rule 213(f)

One of the most consequential uses of interrogatories in Illinois is witness disclosure. When asked through an interrogatory, a party must identify every witness it plans to call at trial and provide specific information depending on the category of witness.¹ Rule 213(f) creates three categories, and the disclosure obligation escalates with each:

Lay witnesses. People who testify about facts they personally observed. For each one, the party must identify the subjects they will testify about. The answer is adequate if it gives reasonable notice of the expected testimony, accounting for the practical limits on what the party actually knows about the witness’s knowledge.
Independent expert witnesses. Experts who are not the party, the party’s employee, or a retained expert. A treating physician in a personal injury case is a common example. For each, the party must identify the subjects of the testimony and the opinions it expects to present, under the same reasonable-notice standard.
Controlled expert witnesses. Experts who are the party, the party’s employee, or a retained expert, such as a hired accident reconstructionist. These carry the most detailed disclosure: the subject matter, the expert’s conclusions and the bases for them, the expert’s qualifications, and any reports the expert prepared about the case.

Rule 213(g) spells out the consequences of incomplete disclosure. A witness’s direct examination at trial is limited to the information disclosed in the party’s interrogatory answers or in a discovery deposition. Testimony not previewed in either place can be objected to and excluded.¹ A party can avoid exclusion only by showing good cause. In practice, Illinois courts enforce the rule strictly, and an undisclosed witness or a surprise opinion can be barred entirely.

The Duty to Update Your Answers

Answering interrogatories is not a one-time obligation. Under Rule 213(i), a party must promptly supplement or amend any prior answer whenever new or additional information becomes available.³ If you identified three witnesses in your original answers and later decide to call a fourth, you have to update the response. If your expert changes an opinion after reviewing new evidence, you have to disclose the change.

This ongoing duty trips up parties more often than the initial response does. Months pass between original answers and trial, and facts shift: new witnesses emerge, treatment continues, losses grow. Failing to supplement triggers the same exclusion consequences that apply to the original disclosure, so testimony or evidence that was not disclosed through a timely supplemental answer can be barred at trial under Rule 213(g). Calendaring periodic reviews of your interrogatory answers throughout the life of the case is safer than waiting until trial preparation to notice what was missed.

What Happens If the Other Side Won’t Answer

When a party refuses to answer, gives evasive responses, or hides behind improper objections, the remedy is a motion to compel. Illinois requires a step first. Under Rule 201(k), the moving party must certify that their trial attorney personally consulted with opposing counsel and made reasonable efforts to resolve the dispute without court involvement.⁴ If opposing counsel was unavailable or unreasonable, the motion must say so specifically. A motion that skips the certification can be denied on procedural grounds alone.

If the court grants the motion and finds the original refusal was without substantial justification, Rule 219(a) requires the non-compliant party, or their attorney, or both, to pay the reasonable expenses the other side incurred in bringing the motion, including attorney fees.⁵ The rule says “shall require,” making the fee award mandatory once the court finds the refusal unjustified.

Continued defiance after a court order escalates the consequences. Under Rule 219(c), the court can impose any of the following:

Stay the proceedings until the party complies.
Bar the party from filing any pleading related to the disputed issue.
Bar specific claims, counterclaims, or defenses.
Prohibit a witness from testifying about the issue.
Enter a default judgment against the offending party or dismiss the case entirely.
Strike portions of the party’s pleadings and enter judgment on those issues.
Order prejudgment interest on any eventual money judgment for the period of delay caused by the misconduct.

The court can also impose monetary penalties and attorney fees on top of any of these sanctions, and willful misconduct can carry especially steep penalties.⁵ Default judgment as a discovery sanction is reserved for serious or repeated violations, but Illinois courts do impose it when parties ignore court orders long enough.

1
Illinois Courts. Illinois Supreme Court Rule 213 – Written Interrogatories to Parties
2
Supreme Court of Illinois. Illinois Supreme Court Rule 214 – Discovery of Documents, Objects, and Tangible Things-Inspection of Real Estate
3
Illinois Courts. Illinois Supreme Court Rule 213 – Written Interrogatories to Parties
4
Supreme Court of Illinois. Illinois Supreme Court Rule 201 – General Discovery Provisions
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Supreme Court of Illinois. Illinois Supreme Court Rule 219 – Consequences of Refusal to Comply with Rules or Order Relating to Discovery or Pretrial Conferences