Additionally, court rule provides:

Each expert witness whom a party expects to call at the trial shall file with the court a written report, which shall be exchanged and filed with the court no later than 60 days before the date set for trial, and reply reports, if any, shall be exchanged and filed no later than 30 days before such date. 2


In view of these provisions, counsel must anticipate that there will be substantial pretrial disclosure with respect to a testimonial expert of not only the conclusions reached but also all of the underlying data upon which the expert has relied. Accordingly, before conveying any case-specific information to a testimonial expert, the attorney must consider the impact of ultimate disclosure to the opposing party.

Beyond pretrial disclosure, the practitioner must also be concerned with in-court disclosure. Most fundamentally, CPLR 4515 requires the expert witness, upon cross-examination, to disclose the specific bases and other supporting criteria underlying his or her opinion.3 Additionally, it must be remembered that once the witness is put on the stand to testify, the adversary will be entitled to inspect any document used by witness to refresh his or her recollection, whether that refreshment occurred on the stand4 or prior to taking the stand.5 This right of adversarial inspection extends even to documents which otherwise would be privileged, their use for the purpose of refreshing the witness’ recollection having been held to waive the privilege.6

Accordingly, from the perspective of the proponent of the testifying expert, extreme care must be exercised in presenting information to the witness, lest inadvertent disclosure ensue. From the perspective of the cross-examiner, of course, it is advisable, at the outset of cross-examination, to inquire as to what writings, if any, the witness has reviewed in preparation for his or her testimony and demand production of same, as well as a recess to review the documents.

Attorney Work Product

In sharp contrast to the broad disclosure requirements applicable to testimonial experts, communications and data flow between counsel and nontestimonial experts, i.e., trial consultants, enjoy substantial confidentiality safeguards.

The attorney work product doctrine is rooted in the seminal U.S. Supreme Court decision in Hickman v. Taylor7 and, in New York, finds expression in CPLR 3101(c), which provides that the “work product of an attorney shall not be obtainable” in disclosure. CPLR 3101(d)(2) provides substantial, though less absolute, protection for material prepared for litigation:

Subject to the provisions of paragraph one of this subdivision, materials otherwise discoverable under subdivision (a) of this section and prepared in anticipation of litigation or for trial by or for another party, or by or for that other party’s representative (including an attorney, consultant, surety, indemnitor, insurer or agent), may be obtained only upon a showing that the party seeking discovery has substantial need of the materials in the preparation of the case and is unable without undue hardship to obtain the substantial equivalent of the materials by other means. In ordering discovery of the materials when the required showing has been made, the court shall protect against disclosure of the mental impressions, conclusions, opinions or legal theories of an attorney or other representative of a party concerning the litigation.