This is Part V in a series of articles explaining the fundamentals of commercial division practice.

The article addresses key components of expert discovery in the commercial division. Part I in the series, addressing the first steps taken when litigating in the commercial division, can be found here; Part II, addressing initial steps such as filing and pleading, can be found here; Part III, addressing the timeline of litigation in the commercial division, can be found here; and Part IV, addressing discovery, can be found here.

Generally

Expert discovery in the commercial division is much more formal than in other divisions of New York Supreme Court. The commercial division rules on experts are patterned off the Federal Rules and therefore contain specific disclosure requirements (and penalties for failing to comply). Rule 13(c), discussed below, spells out what is required.

Note that expert disclosures are baked into the commercial division rules at several inflection points, such that disputes involving expert testimony and discovery do not hinder the case from moving forward:

• Prior to each preliminary and compliance conference, the parties must discuss the “timing and scope of expert disclosure under Rule 13(c)” (22 NYCRR Section 202.70[g], Rules of the commercial division [Comm’l Div.], Rule 8[a]).  
• The Note of Issue and Certificate of Readiness, which is required for the case to proceed to trial, cannot be filed until expert disclosures are complete (Comm’l Div. Rule 13[c]). 
• Prior to the final pretrial conference, the court can direct that the parties meet and confer to identify non-disputed aspects of proposed expert testimony and memorialize their agreement in writing (Comm’l Div. Rule 30[d]).  

Parties should therefore retain experts early and carefully consider how they will impact case strategy to avoid any delays.

Rule 13(c)

Rule 13(c) sets out most of the requirements for expert disclosures, including timing, disclosures, and contents of the report.

1. Timing:  If any party intends to introduce expert testimony at trial, at least 30 days before fact discovery closes, the parties must confer about a schedule for expert disclosures.  Expert disclosures must be completed four months after fact discovery closes.  If the parties cannot agree on a timeline, they must request a conference with the court. 

Note that the parties must “strictly comply” with timing requirements (22 NYCRR Section 202.20-e[a]). For example, if a party conditions the deposition of an opponent’s witness on the opponent’s production of documents by a certain date, and the opponent fails to produce the documents by the deadline, the party seeking the disclosure can ask the court to bar their opponent from producing those documents at trial (22 NYCRR Section 202.20-e[b]).

As another example, Rule 13(c) specifically states that late expert disclosures “will be precluded from use at trial” except for good cause.

In the event of late disclosure, courts will scrutinize the party’s proffered rationale (compare Mone v. Karambiri, No. 651702/2014, 2019 WL 2179448, at *1–2 [N.Y. Sup. Ct. May 16, 2019] [denying motion to exclude expert testimony by affidavit when parties did not set a timeline for expert discovery and movant did not show prejudice] with Nexbank v. Soffer, No. 652072/2013, 2018 WL 2282884, at *2, 4–5 [N.Y. Sup. Ct. May 18, 2018] [disallowing late report based on change of strategy following summary judgment decision] [both decided under different standard—intentional or willful failure to disclose and prejudice to opposing party, see Keyspan Gas East Corp. v. Munich Reinsurance America, Inc., No. 604715/1997, 2016 WL 1258500, at *4 (N.Y. Sup. Ct. Mar. 30, 2016)—but demonstrating scrutiny]).

1. Disclosures:  As part of the schedule for disclosures, the parties must agree on when they will disclose the identity of their experts and exchange expert reports.  Additionally, they must agree on when depositions of identified experts will take place.  

The commercial division rule is notably different from the CPLR expert rule governing other parts of New York Supreme Court, which does not require expert reports or depositions (in most cases, depositions of experts are not even permitted) (see CPLR 3101 [d] [1] [scope of expert disclosures]; [d] [1] [iii] [requiring “special circumstances” to depose most experts]). Note that depositions may be remote (Comm’l Div. Rule 37[a]).

1. Contents of expert report:  Reports must be provided by experts specifically retained to provide expert testimony or party employees whose duties regularly involve giving expert testimony.  Reports must contain (A) the expert’s opinions and grounds therefore, (B) data and information relied on in reaching those opinions, (C) any exhibits that will be used to summarize or support the opinions, (D) the expert’s qualifications (including all publications for the past 10 years), (E) all cases in which the expert testified at a deposition or trial in the past four years, and (F) compensation information.  

As with timing, courts may require that expert reports strictly comply with this rule (see, e.g., Taxi Tours Inc. v. Go New York Tours Inc., 211 N.Y.S.3d 326, 328–29 (2024) [upholding exclusion of expert report and testimony when report did not disclose data underlying opinions in report]; Pope Invs. II LLC v. Belmont Partners, LLC, 186 N.Y.S.3d 148, 150 (2023) [upholding exclusion of testimony by former employee who proponent characterized as “hybrid witness” because he lacked personal knowledge of facts and did not comply with expert disclosure rules]).

Finally, note that expert reports must be sworn (Frenk v. Solomon, No. 650298/2013, 2018 WL 4300960, at *3 [N.Y. Supr. Ct., N.Y. Cnty. Sept. 7, 2018], aff’d, 173 A.D. 3d 490 [1st Dep’t 2019], appeal denied, 34 N.Y.3d 909 [2020] [court cannot rely on unsworn expert opinion], citing Comm’l Div. Rule 13[c]).

If they are sworn, they may be considered by the court on summary judgment (see, e.g., Sabourin v. Chodos, 194 A.D.3d 660, 662 [1st Dep’t 2021] [expert affidavits raised issue of fact precluding summary judgment]; Bd. of Managers of 141 Fifth Ave. Condo v. 141 Acquisition Assocs. LLC, et al., 71 Misc. 3d 1210[A] [N.Y. Supr. Ct., N.Y. Cnty. 2021] [same]).

Disputes and Consequences

Though most discovery disputes are dealt with through the measures set forth in Rule 14, Rule 13(c) provides that objections to expert disclosure procedures should be raised with the court by requesting a conference. Also, as noted above, failure to comply with expert disclosure rules can result in the expert’s testimony being excluded from trial.

Motions in limine are commonly filed to exclude expert testimony. The details of those motions are outside the scope of this article. But note that New York still follows the Frye standard (Frye v. U.S., 293 F. 1013 [App. D.C. 1923]; see, e.g., Ghazala, 214 N.Y.S.3d at 749-50).

To qualify as an expert under Frye, the court will determine whether the expert’s testimony is “based on scientific principal or procedure that has been ‘sufficiently established to have gained general acceptance in the particular field in which it belongs’” (MBIA Ins. Corp. v. Countrywide Home Loans, Inc., 30 Misc. 3d 1201(A), *5 [N.Y. Supr. Ct., N.Y. Cnty. 2010]).

Lack of knowledge in a particular field, though, goes to weight rather than admissibility (Doctors Allergy Formula, LLC v. Valeant Pharms. Int’l, 78 Misc. 3d 1237[A] [N.Y. Supr. Ct., N.Y. Cnty. 2023] [“Criticizing expert testimony based on the expert's alleged lack of knowledge in a particular area of expertise goes to the weight and not the admissibility of the testimony.”]). In the event of a dispute, the court can order a Frye hearing (where the expert is cross-examined about the matters of their report) to determine admissibility [id.].

An exception to the strict compliance the commercial division typically requires with expert disclosure rules: a party is not necessarily precluded from using an expert affidavit at summary judgment even if the party a party fails to disclose the expert (CPLR 3212 [b]; see also CPLR 3101 [d] [1] [expert disclosure rule for non-commercial division parts]).

Something more than failure to disclose, alone, may be required to preclude use of the expert affidavit (see, e.g., Framan Mech., Inc. v. Dormitory Auth. of State of N.Y., 63 Misc. 3d 1218[A] [N.Y. Supr. Ct. 2019] [“Thus, although Arch did not timely identify an expert prior to DASNY’s motion for summary judgment, CPLR 3212 (b) obliges the court to consider any expert proof submitted in opposition to the motion. . . . [T]he court still cannot decline to consider the reports on summary judgment solely on that basis.”]).

Up Next

Part VI of our series will address motion practice in the Commercial Division.

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Reprinted with permission from the February 5, 2025 issue of New York Law Journal. © 2025 ALM Media Properties, LLC. Further duplication without permission is prohibited. All rights reserved.