At A Glance
Summary: Treating physician expert disclosure is mandatory in the Third Department when a doctor will offer causation opinions or other expert testimony at trial.
A plaintiff cannot avoid expert disclosure rules by labeling a doctor as a “treating physician.” If the doctor will offer causation or expert opinion testimony, the plaintiff must comply with CPLR § 3101(d).
Court: New York Appellate Division, Third Department
Decision Date: January 29, 2026
Case: Dewan-Zemko v Hunter Mountain Ski Bowl, Inc., 2026 NY Slip Op 00413 (1st Dept 2026)
Topic: Expert Disclosure Under CPLR § 3101(d) and Treating Physician Testimony
The Court’s Decision
Under CPLR § 3101(d)(1)(i), a party who intends to offer expert testimony at trial must provide timely expert disclosure identifying the expert, the subject matter of the testimony, the substance of the facts and opinions expected to be offered, and the grounds for those opinions.
From A Claims Perspective
In the Third Department, a plaintiff cannot avoid expert disclosure rules by labeling a doctor as a “treating physician.” If the doctor will offer causation or expert opinion testimony, the plaintiff must comply with CPLR § 3101(d).
In a defense-friendly decision with real risk-management implications, the Court affirmed the preclusion of the plaintiff’s treating physician from offering expert causation testimony due to repeated failures to comply with CPLR § 3101(d)(1)(i) and local disclosure rules.
The ruling reinforces a strict, no-exceptions approach to expert disclosure in the Third Department, even when the proposed expert is a treating physician.
What Happened
After an earlier appeal denying summary judgment, the plaintiffs disclosed, well past applicable deadlines, their intent to call a treating physician as a medical causation expert at trial.
The defendant moved to preclude the testimony, citing (1) untimely disclosure under Third Department practice rules, (2) prior court directives ordering compliance, (3) repeated requests for expert disclosure; and (4) a prior, lesser sanction that failed to correct the conduct.
Supreme Court granted preclusion, and the plaintiffs appealed, arguing that treating physicians should be exempt from expert disclosure requirements based on authority from the other Appellate Division departments.
The Decision
The Third Department affirmed preclusion, expressly declining to follow the more lenient approaches taken by the First, Second, and Fourth Departments.
The Court reiterated that treating physicians are not exempt from CPLR § 3101(d)(1)(i). The burden of proper and timely disclosure rests squarely on the party offering the expert. The Court reasoned that the defendants are not required to guess which of many treating providers might be offered as experts at trial.
Notably, the plaintiffs failed to argue that Supreme Court abused its discretion, choosing instead to ask the Court to adopt other departments’ rules and foreclosing any fallback position.
Why This Matter
For claims professionals and defense counsel, this decision is a procedural risk-management win:
- It limits surprise expert testimony late in the litigation;
- It strengthens leverage in high-exposure personal injury cases;
- It rewards disciplined discovery enforcement; and
- It provides a clear roadmap for motions to preclude in the Third Department
This is impactful in cases with voluminous medical records and multiple treating providers, where causation opinions can drive settlement value.
What to Know
- The Third Judicial District has an additional expert disclosure rule
- In the Third Department, a treating physician is not automatically exempt from expert disclosure requirements
- Medical records and authorizations do not substitute for CPLR § 3101(d) disclosure
Practice Pointers
- Calendar expert disclosure deadlines early
- Request compliance with discovery demands well before trial
- Move to preclude expert testimony where plaintiffs fail to timely comply with CPLR § 3101(d).
- Emphasize prejudice based on volume of treating providers, and prior court warnings
Handled correctly, expert disclosure issues can materially reduce trial risk and settlement pressure, and this decision confirms that, at least in the Third Department, CPLR § 3101(d) has teeth.
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Matthew Lerner is a New York civil litigation and appellate attorney at Gerber Ciano Kelly Brady LLP and the publisher of New York Civil Law. He writes about New York appellate decisions, insurance coverage, Labor Law, and litigation strategy for claims professionals and trial attorneys.
Primary Authority
The Third Department held that a plaintiff’s treating physician may be precluded from offering expert causation testimony where the party fails to comply with CPLR § 3101(d) expert disclosure requirements and ignores court-ordered disclosure deadlines.
(Dewan-Zemko v Hunter Mountain Ski Bowl, Inc., 2026 NY Slip Op 00413 (1st Dept 2026)
Sources
- CPLR § 3101(d)(1)(i) — Expert witness disclosure requirements
- Third Judicial District Expert Witness Disclosure Rule
- Dewan-Zemko v Hunter Mountain Ski Bowl, Inc., 2026 NY Slip Op 00413 (1st Dept 2026)
Questions This Case Answers
- Does any New York trial court have rules in addition to CPLR § 3101(d) concerning the disclosure of expert witnesses?
- Must a plaintiff designate a treating physician as an expert witness to comply with CPLR § 3101(d)?
- When will courts preclude late expert disclosure?
- Can discovery violations lead to expert preclusion?
- Are treating physicians exempt from CPLR § 3101(d) expert disclosure?
- When can a treating physician be precluded from testifying as an expert in New York?
- Does a treating physician offering causation opinions require expert disclosure under New York’s CPLR?
- Can courts preclude expert testimony for late CPLR § 3101(d) disclosures?
- What are the expert disclosure rules in the New York’s Third Judicial District?
Related Topics
CPLR § 3101(d), expert disclosure, treating physician expert testimony, expert preclusion, New York personal injury procedure, discovery sanctions, Third Department practice.
Photo Credit: Hush Naidoo Jade Photography