Third Department Reaffirms: Treating Physicians Must Be Disclosed as Experts Under CPLR 3101(d)(1)(i) to Testify on Causation

1. Introduction

Dewan-Zemko v Hunter Mtn. Ski Bowl, Inc. (2026 NY Slip Op 00413 [3d Dept Jan. 29, 2026]) addresses a recurring New York disclosure problem: whether and when a party must serve expert disclosure for a treating physician who will offer expert opinions—particularly causation—at trial.

Plaintiffs (Tracy Dewan-Zemko et al.) sought to call Dewan-Zemko’s treating physician, Michael Weintraub, as a medical expert on causation. Defendant (Hunter Mountain Ski Bowl, Inc.) moved to preclude the testimony, arguing plaintiffs’ expert disclosure was untimely under the Third Judicial District’s practice rules and did not comply with CPLR 3101(d)(1)(i). Supreme Court granted preclusion, citing repeated requests for disclosure, prior directions to comply, and a prior lesser sanction for a CPLR 3101(d)(1)(i) violation.

On appeal, plaintiffs principally asked the Third Department to adopt the more permissive “treating physician” approaches used in other Departments. The Third Department declined, reaffirming its stricter rule.

2. Summary of the Opinion

  • The Third Department reiterated that CPLR 3101(d)(1)(i) requires expert disclosure for any medical professional—including a treating physician—if that person will give expert testimony (including causation).
  • The Court declined to follow the “blanket rule” used at times in other Departments that treating physicians may testify on causation without CPLR 3101(d) expert notice.
  • The Court emphasized the proponent’s burden to serve disclosure; an opponent is not required to sift voluminous medical records to guess which provider will be offered as an expert.
  • Although the appeal posture could have raised whether Supreme Court abused its discretion in imposing preclusion, the Court did not reach that issue because plaintiffs did not argue it as an alternative ground for reversal.
  • Procedurally, the appeal from the earlier October 7, 2024 order was dismissed because the October 16, 2024 amended order superseded it (citing Delosh v Amyot).

3. Analysis

3.1. Precedents Cited

A. The governing statute and Court of Appeals framing

The Court began with the text of CPLR 3101(d)(1)(i) and the Court of Appeals’ articulation of what must be disclosed: subject matter, substance of facts/opinions, qualifications, and grounds. It cited Rivera v Montefiore Med. Ctr., 28 NY3d 999 (2016), both for the content requirements and for the general principle that whether to preclude expert testimony for noncompliance is a discretionary determination.

B. The “Sister Departments” approaches and the Departmental split

The majority opinion mapped a notable split within the Appellate Division:

  • Second Department “blanket rule” line: The opinion describes a line of cases stating that a treating physician may testify regarding causation despite failure to provide CPLR 3101(d)(1) notice, citing Duman v Scharf, Jing Xue Jiang v Dollar Rent a Car, Inc., and Mantuano v Mehale, while acknowledging tension/limits reflected by Hughes v Webb.
  • Fourth Department’s earlier alignment with the blanket rule: The opinion lists decisions such as Andrew v Hurh, Rokitka v Barrett, Bonner v Lee, Casey v Tan, Stark v Semeran, and Rook v 60 Key Ctr., which had followed that approach.
  • First Department (and more recent Fourth Department) “records fully disclosed” approach: The opinion notes the First Department’s view that where a treating physician’s records/reports are fully disclosed, lack of CPLR 3101(d)(1) notice may not warrant preclusion because surprise/prejudice is negated—citing Breen v Laric Entertainment Corp. (and “accord” Harris v Campbell), as well as Hamer v City of New York and Ryan v City of New York. It also notes contrary/limiting First Department cases, including Gjeka v Iron Horse Transp., Inc. and Thomas v 14 Rollins St. Realty Corp.
  • First Department historical references: The opinion includes Finger v Brande and McGee v Family Care Servs. as part of the broader discussion of Appellate Division treatment.

The practical takeaway from this survey is that other Departments often analyze treating-physician testimony through the lens of whether the opponent already has the records and thus lacks surprise, while the Third Department treats expert disclosure as an affirmative obligation regardless of record production.

C. The Third Department’s own precedent—affirmed and entrenched

The opinion squarely reaffirms the Third Department’s rule, relying on:

  • Schmitt v Oneonta City Sch. Dist., 151 AD3d 1254 (3d Dept 2017) (CPLR 3101(d)(1)(i) requires disclosure of any medical professional expected to give expert testimony).
  • Freeman v State of New York, 206 AD3d 1102 (3d Dept 2022) (continuing enforcement of the rule and addressing remedial considerations in the face of the inter-department split).
  • Colucci v Stuyvesant Plaza, Inc., 157 AD3d 1095 (3d Dept 2018) (the proponent bears the burden of “particular details”; opposing counsel need not mine voluminous records to infer qualifications and opinions).
  • The concurrence adds additional Third Department decisions applying the same framework: Norton v Nguyen and Chapman v State of New York.
  • The opinion also references the leading treatise: David D. Siegel & Patrick M. Connors, New York Practice § 348A.

D. Stare decisis authorities (concurrence)

Justice Aarons’ concurrence explains why the panel should not change course absent a compelling justification, invoking:

  • Grady v Chenango Val. Cent. Sch. Dist., 40 NY3d 89 (2023) (high threshold for overruling precedent).
  • People v Peque, 22 NY3d 168 (2013), cert denied 574 US 840 (2014) (examples of when overruling may be warranted: unworkability, conflict with broader doctrine, injustice).
  • SanMiguel v Grimaldi, ___ NY3d ___, 2025 NY Slip Op 05780 (2025) (reinforcing stare decisis principles).

E. Appellate procedure on superseding orders

The Court dismissed the appeal from the original order because the amended order superseded it, citing Delosh v Amyot, 206 AD3d 1194 (3d Dept 2022).

3.2. Legal Reasoning

  1. Textual anchor: The majority stressed the “plain language” of CPLR 3101(d)(1)(i), which requires disclosure of “each person” expected to testify as an expert and detailed information about what the expert will say and why. The statute does not carve out treating physicians.
  2. Allocation of burden: Citing Colucci v Stuyvesant Plaza, Inc., the Court treated expert disclosure as an affirmative obligation on the proponent, rejecting the notion that record production shifts work to the opponent to “ferret out” who will be offered as an expert and what opinions will be offered.
  3. Practical prejudice and notice: The Court highlighted the case-specific context: plaintiffs had executed authorizations for records from “over 15 separate medical professionals.” In that circumstance, the defendant could not reasonably be expected to guess which provider would be designated as an expert witness. This reasoning functions as a practical rebuttal to the “records fully disclosed” approach used elsewhere.
  4. Scope of appellate review constrained by the arguments made: The Court noted that the “normal” next question would be whether Supreme Court abused its discretion in ordering preclusion (as framed in Rivera v Montefiore Med. Ctr.), but it refused to reach that issue because plaintiffs did not present it as an alternative argument. The decision thus underscores a litigation lesson: appellate courts generally decide only the issues the appellant properly advances.
  5. Concurrence—stare decisis as the limiting principle: Justice Aarons agreed with affirmance not as a policy choice, but because plaintiffs did not meet the demanding standard to overturn the Third Department’s established interpretation. He also emphasized that Supreme Court’s finding of prejudice was “unchallenged on appeal,” undercutting the plaintiffs’ central “no surprise” argument.

3.3. Impact

  • Within the Third Department: The rule is reaffirmed and sharpened: parties must serve CPLR 3101(d)(1)(i) expert disclosures for treating physicians if they will offer expert opinions (including causation), and failure to comply— especially in the face of repeated requests and court directives—can result in preclusion.
  • Departmental non-uniformity remains: The decision openly preserves a split with other Departments. Until the Court of Appeals resolves the issue or the Legislature amends CPLR 3101(d), venue will continue to materially affect how treating physician testimony is disclosed and litigated.
  • Strategic consequences for practitioners:
    • Assume treating physicians are “experts” if causation, prognosis, permanency, future treatment, or disability opinions will be offered.
    • Do not rely on record exchange alone (e.g., CPLR 3121 / 22 NYCRR 202.17 practice) as a substitute for CPLR 3101(d)(1)(i) notice.
    • Track and comply with local practice-rule timing requirements; late disclosure risks outright preclusion.
    • On appeal, preserve alternative arguments (e.g., abuse of discretion, lack of prejudice, lesser sanctions).
  • Trial-court management: The decision supports robust enforcement of disclosure deadlines and sanctions where noncompliance is repeated and case management orders have been ignored.

4. Complex Concepts Simplified

CPLR 3101(d)(1)(i) “expert disclosure”
A required pretrial disclosure identifying expert witnesses and summarizing what they will testify to, their qualifications, and the basis for their opinions. It is designed to reduce surprise and permit meaningful preparation.
Treating physician vs. “retained” expert
A treating physician provides care and creates records for medical purposes, not litigation. A retained expert is hired to evaluate and testify. This case holds that, in the Third Department, a treating physician becomes subject to CPLR 3101(d) when the party intends to elicit “expert” opinions (like causation), not merely factual treatment history.
Preclusion
A sanction barring a witness from giving certain testimony (here, expert testimony). It can effectively decide a case if the excluded testimony is central to an element like causation.
“Good cause” proviso in CPLR 3101(d)(1)(i)
The statute contemplates that late expert disclosure may be excused where the party, for good cause, retained an expert too close to trial to provide earlier notice. Even then, the court may craft a “just” remedy (e.g., adjournment, supplemental disclosure), rather than automatic preclusion.
Stare decisis
The principle that courts follow their prior decisions for stability and predictability. The concurrence emphasizes that changing an established Departmental rule requires a compelling justification (e.g., the rule is unworkable or unjust).
Superseding amended order
When an amended order replaces an earlier one, an appeal from the earlier order is typically dismissed because it no longer has independent legal effect (here, under Delosh v Amyot).

5. Conclusion

Dewan-Zemko v Hunter Mtn. Ski Bowl, Inc. cements the Third Department’s rule that a treating physician expected to offer expert testimony—especially on causation—must be disclosed under CPLR 3101(d)(1)(i), and that courts may preclude such testimony for noncompliance. The Court declined to harmonize its approach with other Departments, prioritizing statutory text and the proponent’s burden of clear expert notice over assumptions drawn from medical record exchange. The concurrence frames the outcome as driven by stare decisis and the appellants’ failure to undermine findings of prejudice or to preserve alternative appellate theories.