New York Rules Regarding Expert Witness Depositions and Interrogatories 

Under New York Civil Practice Law and Rules (“CPLR”) Section 3101(d)(1)(iii), depositions and interrogatories of experts (or any form of discovery other than that provided for in CPLR Section 3101(d)(1)(i), discussed below) are only available on a showing of special circumstances. A court will generally only find that special circumstances are present “where physical evidence is ‘lost or destroyed’ or ‘where some other unique factual situation exists,’ such as proof ‘that the information sought to be discovered cannot be obtained from other sources.’” Ruthman v. Nardiello, 732 N.Y.S.2d 455, 457 (N.Y. App. Div. 2001); see also Falcone v. Karagiannis, 2011 N.Y. Misc. LEXIS 1701, at *8 (Apr. 6, 2011) (finding special circumstances to be present and allowing deposition of a testifying expert where “the cause of decedent’s death [was] a significant issue and the manner, means and methods of conducting the autopsy and examining the results [were] peculiarly within [the expert]’s knowledge and not available through other sources). Demonstrating that evidence would be relevant is insufficient standing alone. Ruthman, supra, at 457. Note, though, that according to the comments to the CPLR, parties may mutually agree to depose each other’s experts, and that such mutual agreement conforms to the general standards of practice in the Commercial Division of the New York State Supreme Court (see below for a discussion of New York’s expert witness discovery rules for cases in the Commercial Division of New York courts). 

New York Expert Witness Reports and Disclosures Rules 

Under New York Civil Practice Law and Rules (“CPLR”) Section 3101(a)(3), expert witnesses must provide “full disclosure of all matter material and necessary” to the case for which they are retained. Section 3101(d)(1)(i) further requires each party to produce information about its experts upon request by the opposing party. This information must include the identity of the expert, the subject matter on which the expert will testify, the facts and opinions on which the expert will testify, the basis for those facts and opinions, and the qualifications of the expert. It is important to note that, although the CPLR does not explicitly make this distinction, these requirements only apply to experts whom a party expects to call at trial. The comments to the CPLR make clear that an expert retained only for consulting purposes in preparation for a case is exempt from the disclosure requirements. The comments suggest that such experts are “an adjunct to the lawyer’s strategic thought processes” such that the consulting expert’s communications with the attorney qualify as attorney work-product or the mental impressions of the attorney, which are completely exempted from discovery under CPLR Section 3101(c) and 3101(d)(2).

It is also important to note that Section 3101(d)(1)(i) carves out a slight exception for experts retained in medical, dental, or podiatric malpractice cases. In those cases, a party may omit the names of medical, dental, or podiatric experts, but must make all the other disclosures listed above. 

Rules Regarding Lawyer-Expert Communications, Draft Expert Witness Reports, Expert Witness Notes, Etc. in New York 

The comments to the CPLR make clear that the special circumstances test used to determine whether an expert may be subject to further discovery such as deposition (discussed above) also applies to disclosure of draft and final reports by the expert and “laboratory reports, computer printouts, or other materials compiled by the expert.” Accordingly, an experts draft reports, notes, etc. may only be subject to disclosure “where physical evidence is ‘lost or destroyed’ or ‘where some other unique factual situation exists,’ such as proof ‘that the information sought to be discovered cannot be obtained from other sources.” Ruthman, supra, at 457. 

New York Expert Witness Discovery Rules for Commercial Division Cases

In New York, expert witness discovery in commercial cases differs in certain respects, most importantly regarding the availability of expert depositions and the exchange of expert reports, from the general expert witness discovery rules summarized above. These differences generally provide for more liberal discovery of experts in cases before the Commercial Division. Specifically, Rule 13(c) under Section 202.70 of the New York Uniform Rules of the Trial Courts provides that “identification of experts, exchange of reports, and depositions of testifying experts” must be completed within four months following the completion of fact discovery. Depositions generally may not exceed seven hours.

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