(a) A party shall disclose each person who may be called by that party to testify as an expert witness at trial, and all documents that may be offered in evidence in lieu of such expert testimony, in accordance with this section. The requirements of Section 13-15 shall apply to disclosures made under this section.
Section 13-4.—Experts
Current through August 12, 2025 (2026 Practice Book edition) · Last verified July 9, 2026
In one sentenceThis rule requires parties to disclose their trial expert witnesses, sets out what must be revealed about each expert’s opinions and supporting materials, governs expert depositions and fees, and establishes a court-approved schedule for expert discovery with sanctions for noncompliance.
Full Text of Section 13-4
(b) A party shall file with the court and serve upon counsel a disclosure of expert witnesses which identifies the name, address and employer of each person who may be called by that party to testify as an expert witness at trial, whether through live testimony or by deposition. In addition, the disclosure shall include the following information:
(1) Except as provided in subdivision (2) of this subsection, the field of expertise and the subject matter on which the witness is expected to offer expert testimony; the expert opinions to which the witness is expected to testify; the substance of the grounds for each such expert opinion; and the written report of the expert witness, if any. The report shall not be filed with the court. Disclosure of the information required under this subsection may be made by making reference in the disclosure to the written report of the expert witness containing such information.
(2) If the witness to be disclosed hereunder is a health care provider who rendered care or treatment to the plaintiff, and the opinions to be offered hereunder are based upon that provider’s care or treatment, then the disclosure obligations under this section may be satisfied by disclosure to the parties of the medical records and reports of such care or treatment. A witness disclosed under this subsection shall be permitted to offer expert opinion testimony at trial as to any opinion as to which fair notice is given in the disclosed medical records or reports. Expert testimony regarding any opinion as to which fair notice is not given in the disclosed medical records or reports must be disclosed in accordance with subdivision (1) of subsection (b) of this section. The parties shall not file the disclosed medical records or disclosed medical reports with the court.
(3) Except for an expert witness who is a health care provider who rendered care or treatment to the plaintiff, or unless otherwise ordered by the judicial authority or agreed upon by the parties, the party disclosing an expert witness shall, upon the request of an opposing party, produce to all other parties all materials obtained, created and/ or relied upon by the expert in connection with his or her opinions in the case within fourteen days prior to that expert’s deposition or within such other time frame determined in accordance with the Schedule for Expert Discovery prepared pursuant to subsection (g) of this section. If any such materials have already been produced to the other parties in the case, then a list of such materials, made with sufficient particularity that the materials can be easily identified by the parties, shall satisfy the production requirement hereunder with respect to those materials. If an expert witness otherwise subject to this subsection is not being compensated in that capacity by or on behalf of the disclosing party, then that party may give written notice of that fact in satisfaction of the obligations imposed by this subsection. If such notice is provided, then it shall be the duty of the party seeking to depose such expert witness to obtain the production of the requested materials by subpoena or other lawful means.
(4) Nothing in this section shall prohibit any witness disclosed hereunder from offering nonexpert testimony at trial.
(c) (1) Unless otherwise ordered by the judicial authority upon motion, a party may take the deposition of any expert witness disclosed pursuant to subsection (b) of this section in the manner prescribed in Section 13-26 et seq. governing deposition procedure generally. Nothing contained in subsection (b) of this section shall impair the right of any party from exercising that party’s rights under the rules of practice to subpoena or to request production of any materials, to the extent otherwise discoverable, in addition to those produced under subsection (b) of this section, in connection with the deposition of any expert witness, nor shall anything contained herein impair the right of a party to raise any objections to any request for production of documents sought hereunder to the extent that a claim of privilege exists. (2) Unless otherwise ordered by the judicial authority for good cause shown, or agreed upon by the parties, the fees and expenses of the expert witness for any such deposition, excluding preparation time, shall be paid by the party or parties taking the deposition. Unless otherwise ordered, the fees and expenses hereunder shall include only (A) a reasonable fee for the time of the witness to attend the deposition itself and the witness’ travel time to and from the place of deposition; and (B) the reasonable expenses actually incurred for travel to and from the place of deposition and lodging, if necessary. If the parties are unable to agree on the fees and expenses due under this subsection, the amount shall be set by the judicial authority, upon motion.
(d) (1) A party shall file with the court a list of all documents or records that the party expects to submit in evidence pursuant to any statute or rule permitting admissibility of documentary evidence in lieu of the live testimony of an expert witness. The list filed hereunder shall identify such documents or records with sufficient particularity that they shall be easily identified by the other parties. The parties shall not file with the court a copy of the documents or records on such list. (2) Unless otherwise ordered by the judicial authority upon motion, a party may take the deposition of any expert witness whose records are disclosed pursuant to subdivision (1) of subsection (d) of this section in the manner prescribed in Section 13-26 et seq. governing deposition procedure generally. Nothing contained in subsection (d) of this section shall impair the right of any party from exercising that party’s rights under the rules of practice to subpoena or to request production of any materials, to the extent otherwise discoverable, in addition to those produced under subsection (d), in connection with the deposition of any expert witness. (3) Unless otherwise ordered by the judicial authority for good cause shown, or agreed upon by the parties, the fees and expenses of the expert witness for any such deposition, excluding preparation time, shall be paid by the party or parties taking the deposition. Unless otherwise ordered, the fees and expenses hereunder shall include only (A) a reasonable fee for the time of the witness to attend the deposition itself and the witness’ travel time to and from the place of deposition; and (B) the reasonable expenses actually incurred for travel to and from the place of deposition and lodging, if necessary. If the parties are unable to agree on the fees and expenses due under this subsection, the amount shall be set by the judicial authority, upon motion.
(e) If any party expects to call as an expert witness at trial any person previously disclosed by any other party under subsection (b) hereof, the newly disclosing party shall file a notice of disclosure: (1) stating that the party adopts all or a specified part of the expert disclosure already on file; and (2) disclosing any other expert opinions to which the witness is expected to testify and the substance of the grounds for any such expert opinion. Such notice shall be filed within the time parameters set forth in subsection (g).
(f) A party may discover facts known or opinions held by an expert who had been retained or specially employed by another party in anticipation of litigation or preparation for trial and who is not expected to be called as a witness at trial only as provided in Section 13-11 or upon a showing of exceptional circumstances under which it is impracticable for the party seeking discovery to obtain facts or opinions on the same subject by other means.
(g) Unless otherwise ordered by the judicial authority, or otherwise agreed by the parties, the following schedule shall govern the expert discovery required under subsections (b), (c), (d) and (e) of this section. (1) Within 120 days after the return date of any civil action, or at such other time as the parties may agree or as the court may order, the parties shall submit to the court for its approval a proposed Schedule for Expert Discovery, which, upon approval by the court, shall govern the timing of expert discovery in the case. This schedule shall be submitted on a ‘‘Schedule for Expert Discovery’’ form prescribed by the Office of the Chief Court Administrator. The deadlines proposed by the parties shall be realistic and reasonable, taking into account the nature and relative complexity of the case, the need for predicate discovery and the estimated time until the case may be exposed for trial. If the parties are unable to agree on discovery deadlines, they shall so indicate on the proposed Schedule for Expert Discovery, in which event the court shall convene a scheduling conference to set those deadlines. (2) If a party is added or appears in a case after the proposed Schedule for Expert Discovery is filed, then an amended proposed Schedule for Expert Discovery shall be prepared and filed for approval by the court within sixty days after such new party appears, or at such other time as the court may order. (3) Unless otherwise ordered by the court, disclosure of any expert witness under subsection (e) hereof shall be made within thirty days of the event giving rise to the need for that party to adopt the expert disclosure as its own (e.g., the withdrawal or dismissal of the party originally disclosing the expert). (4) The parties, by agreement, may modify the approved Schedule for Expert Discovery or any other time limitation under this section so long as the modifications do not interfere with an assigned trial date. A party who wishes to modify the approved Schedule for Expert Discovery or other time limitation under this section without agreement of the parties may file a motion for modification with the court stating the reasons therefor. Said motion shall be granted if: (A) the requested modification will not cause undue prejudice to any other party; (B) the requested modification will not cause undue interference with the trial schedule in the case; and (C) the need for the requested modification was not caused by bad faith delay of disclosure by the party seeking modification.
(h) A judicial authority may, after a hearing, impose sanctions on a party for failure to comply with the requirements of this section. An order precluding the testimony of an expert witness may be entered only upon a finding that: (1) the sanction of preclusion, including any consequence thereof on the sanctioned party’s ability to prosecute or to defend the case, is proportional to the noncompliance at issue, and (2) the noncompliance at issue cannot adequately be addressed by a less severe sanction or combination of sanctions.
(i) The revisions to this rule adopted by the judges of the Superior Court in June, 2008, effective on January 1, 2009, and the revisions to this rule adopted by the judges of the Superior Court in June, 2009, and March, 2010, shall apply to cases commenced on or after January 1, 2009. The version of this rule in effect on December 31, 2008, shall apply to cases commenced on or before that date.
Amendment History
(P.B. 1978-1997, Sec. 220.) (Amended June 30, 2008, to take effect Jan. 1, 2009; amended June 22, 2009, to take effect Sept. 1, 2009; amended June 21, 2010, to take effect Jan. 1, 2011; amended June 15, 2012, to take effect Jan. 1, 2013; amended June 24, 2016, to take effect Jan. 1, 2017.)
Plain-English Summary
Subsection (a) requires a party to disclose every person it may call as an expert witness at trial and any documents it may offer in place of expert testimony. Subsection (b) spells out what the disclosure must contain: name, address, and employer of each expert, plus — unless the expert is a treating health care provider covered by subdivision (2) — the field of expertise, the subject matter of the testimony, the opinions expected, the grounds for those opinions, and any written report (which itself is not filed with the court, though the disclosure may reference it). For a treating health care provider, disclosure obligations can be satisfied by giving the parties the relevant medical records and reports, and the witness may testify to any opinion for which those records give fair notice; anything else must be disclosed under subdivision (1). Subsection (b)(3) generally requires the disclosing party, on request, to produce all materials the expert obtained, created, or relied on, within fourteen days before the expert’s deposition or per the case’s Schedule for Expert Discovery, unless the expert is an uncompensated treating provider, in which case written notice of noncompensation substitutes for production.
Subsections (c) and (d) govern deposing disclosed experts and experts whose records are used in lieu of live testimony, including how deposition fees and expenses are allocated (generally borne by the party taking the deposition, covering the expert’s attendance and travel time and reasonable travel/lodging expenses, absent a different order or agreement). Subsection (e) covers adopting another party’s already-disclosed expert. Subsection (f) allows discovery of facts or opinions held by a non-testifying expert retained in anticipation of litigation only as provided in Section 13-11 or on a showing of exceptional circumstances making it impracticable to obtain the same information elsewhere. Subsection (g) requires the parties to submit a proposed Schedule for Expert Discovery within 120 days of the return date (or as ordered), with amendment procedures when a new party appears or the parties seek to modify deadlines. Subsection (h) allows the judicial authority, after a hearing, to impose sanctions for noncompliance, but an order precluding expert testimony requires findings that the sanction is proportional to the noncompliance and that no less severe sanction would adequately address it.
Frequently Asked Questions
What must a Connecticut expert witness disclosure include?
Under Section 13-4(b), it must give the expert’s name, address, and employer, plus (except for certain treating health care providers) the field of expertise, subject matter, expected opinions, the grounds for those opinions, and any written report.
Who pays for an expert’s deposition in Connecticut?
Section 13-4(c)(2) and (d)(3) provide that, absent a different order or agreement, the party taking the expert’s deposition pays a reasonable fee for the expert’s attendance and travel time plus reasonable travel and lodging expenses, excluding preparation time.
Can a party discover the opinions of an expert who won’t testify at trial?
Section 13-4(f) allows discovery of a non-testifying, litigation-retained expert’s facts or opinions only as provided in Section 13-11 or on a showing of exceptional circumstances making it impracticable to get comparable information by other means.
Can a court bar an expert from testifying for a disclosure violation?
Yes, but Section 13-4(h) requires the judicial authority to find that preclusion is proportional to the noncompliance and that the problem cannot adequately be fixed with a less severe sanction.
Source & verification. The section text is reproduced verbatim from the
official Connecticut Practice Book (Conn. Practice Book § 13-4). Prescribed by the Judges of the Superior Court of Connecticut (Conn. Gen. Stat. Section 51-14). The plain-English summary is original and written by us. Last verified July 9, 2026. ·
Official source
Also known as: disclosing expert witnesses Connecticutexpert witness deposition fees CTSchedule for Expert Discoverytreating physician expert disclosureprecluding expert testimony sanctionsnon-testifying expert discovery