Pennsylvania Rules Regarding Expert Witness Depositions and Interrogatories


Under Rule 4003.5(a)(2) of the Pennsylvania Rules of Civil Procedure, experts may only be subject to deposition “[u]pon cause shown.” Such a finding of cause appears to be exceedingly rare in Pennsylvania. For an example of a Pennsylvania case in which sufficient cause was shown to permit the deposition of an expert, see Cooper v. Schoffstall, 905 A.2d 482, 495 (Pa. 2006), in which the court held that in order to make the requisite showing of cause, “the proponent of the discovery should demonstrate a significant pattern of compensation that would support a reasonable inference that the witness might color, shade, or slant his testimony in light of the substantial financial incentives.” The court went on to explain, though, that, if cause is shown sufficient to depose an expert, depositions by written interrogatories are favored over oral depositions. Id. (“In keeping with the idea that the discovery along these lines should be of the least burdensome and intrusive kind possible, we believe that the appropriate entry point, upon the showing of cause, is a deposition by written interrogatories.”).


For purposes of expert discovery generally, interrogatories may only be served on the opposing party under Rule 4003.5(a)(1) of the Pennsylvania Rules of Civil Procedure. However, through these interrogatories, a party can require the opposing party to have each expert identified by the interrogatory provide certain information held by the expert, as explained in the following section. Therefore, while interrogatories will generally only be served on the parties themselves, experts may be required to play in role in responding to them.


Pennsylvania Expert Witness Reports and Disclosures Rules


Expert witnesses in Pennsylvania, as in most states, are generally divided into two categories—those who are expected to be called as witnesses at trial and those who are retained for consulting purposes in anticipation of or preparation for litigation, but not expected to be called at trial. Under Rule 4003.5(a)(1) of the Pennsylvania Rules of Civil Procedure, a party will be required to identify all experts it expects to call at trial and to provide the subject matter of the expert’s testimony upon interrogatory from the opposing party. Additionally, a party can require an opposing party to have each expert identified in such interrogatory state the facts and opinions to which the expert is expected to testify and the basis for each opinion. This can be satisfied either by providing an expert report containing this information or by having the expert answer the interrogatory himself.


Experts retained only for consulting purposes, on the other hand, are fully protected from discovery under Rule 4003.5(a)(3) absent a showing of exceptional circumstances under which it is impracticable for the party seeking discovery to obtain facts or opinions on the same subject by other means. The explanatory comments to the Pennsylvania Rules of Civil Procedure explain that demonstrating exceptional circumstances “is a heavy burden,” and provide the example of a consulting expert destroying a relevant object that had been given to the expert for testing as a situation in which the burden may be met. Note that medical experts retained only to examine a party when the mental or physical condition of the party are at issue, and not expected to be called at trial, are excluded from the protections afforded consulting witnesses by Rule 4010(b).

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


Under Rule 4003.5(a)(4) of the Pennsylvania Rules of Civil Procedure, draft expert reports and attorney-expert communications are explicitly protected from discovery “except in circumstances that would warrant the disclosure of privileged communications under Pennsylvania law.” This is a recent development in Pennsylvania, becoming final in July 2014. See In re Amendment of Rule 4003.5 of the Pa. Rules of Civil Procedure, 2014 Pa. LEXIS 1694 (Pa. July 10, 2014).