CPLR 3101(d)(1)

CPLR 3101(d)(1)(i) requires expert disclosure on request but does not itself set a universal pre-note-of-issue deadline. Court rules and orders still require separate review.

Yampolskiy v Baron addresses discretion to consider expert materials on a timely summary judgment motion despite nondisclosure before the note of issue.

This case addresses a common scenario in personal injury litigation: a defendant seeks summary judgment and submits expert materials to support their motion, but failed to properly disclose those experts under CPLR 3101(d)(1)(i). While strict adherence to disclosure rules is important, courts retain discretion to consider expert evidence even when disclosure deadlines are missed, provided certain conditions are met.

The decision reinforces that CPLR 3101(d) preclusion is not automatic and depends heavily on the specific circumstances of each case. Courts must carefully balance procedural compliance with the interests of justice.

Historical note (September 2026): this note reads a 2017 decision on CPLR 3101(d)(1) expert disclosure; the statute is linked in the text. For current expert-disclosure practice in injury cases see expert witnesses in New York car accident cases.

CPLR 3101 at a Glance: Disclosure in New York Civil Practice

CPLR 3101 is the backbone of disclosure in New York civil litigation. Subdivision (a) sets the governing standard: there shall be “full disclosure of all matter material and necessary in the prosecution or defense of an action” — a phrase the courts have long construed liberally in favor of disclosure.

The subdivisions that generate the most motion practice:

• CPLR 3101(a) — full disclosure of all matter material and necessary, regardless of the burden of proof.
• CPLR 3101(d)(1)(i) — expert disclosure. The statute itself contains no automatic deadline, but trial courts may impose them by rule or order — a point the Court of Appeals confirmed in Rivera v Montefiore, discussed in 3101(d) from the Court of Appeals.
• CPLR 3101(d)(2) — materials prepared in anticipation of litigation, discoverable only on a showing of substantial need and undue hardship.
• CPLR 3101(b)-(c) — the privilege carve-outs: privileged matter and attorney work product are immune from disclosure.

Because the expert provision lacks a hard statutory deadline, late disclosure disputes are common. The case law runs from 3101(d) statements that go awry to the recurring question of how much detail is enough to satisfy 3101(d).

Jason Tenenbaum’s Analysis:

Yampolskiy v Baron, 150 AD3d 795 (2d Dept 2017), decided May 3, 2017

"" party’s failure to disclose its experts pursuant to CPLR 3101(d)(1)(i) prior to the filing of a note of issue and certificate of readiness does not divest a court of the discretion to consider an affirmation or affidavit submitted by that party’s experts in the context of a timely motion for summary judgment” (Rivers v Birnbaum, 102 AD3d 26, 31). Under the circumstances of this case, the Supreme Court properly denied the plaintiff’s cross motion to preclude the expert materials submitted by the defendants in support of their motion for summary judgment, as there was no evidence that the failure to disclose the experts was intentional or willful, and there was no showing of prejudice to the plaintiff (see Begley v City of New York, 111 AD3d 5, 36; Salcedo v Weng Qu Ju, 106 AD3d 977, 978; Hayden v Gordon, 91 AD3d 819, 820).”

Key Takeaway

Courts maintain discretion to consider expert evidence even when disclosure deadlines are missed, provided the failure was not intentional or willful and no prejudice resulted. This decision emphasizes that procedural violations don’t automatically preclude expert testimony when justice would be better served by considering the evidence on its merits.

The court nevertheless denied the defendants’ summary judgment motion because their proof failed to address the claimed 90/180-day injury category. Permission to consider an expert’s material did not make that material sufficient.

For the nonjury-trial setting, Market Street’s CPLR 4404(b) appeal connects expert preclusion to a limited new trial. It did not excuse late disclosure as a general practice.

Last reviewed: September 2026 — editorial correction of the statutory-deadline claim, decision year and disposition; historical trial example added.

Connect to the Encyclopedia

• Topic hub: Expert Testimony & Qualifications
• CPLR 3101(d) preclusion requirements and court discretion
• Expert competency standards in New York medical cases
• Expert witness qualifications in medical malpractice litigation
• Foundation requirements for medical malpractice expert testimony
• New York No-Fault Insurance Law
• Another 3101(d) case