One way to impeach the credibility of an expert witness is to show that he derives a significant part of his income from being an expert witness, typically for one side. The Maryland Court of Appeals, in a personal injury case, held that it was proper to allow limited discovery into the finances of the defendant’s (or insurance company’s) expert witness in order to show bias. At the same time, the court made clear that this was not unlimited discovery, and could be kept confidential, and was not necessarily admissible at trial. The decision is useful in collecting case law from other states on this contentious issue, and in containing broad language concerning the need for discovery about the expert witness.

Some excerpts follow:

http://mdcourts.gov/opinions/coa/2010/60a09.pdf

Falik v. Hornage, et al., Nos. 60 & 90 (Md. Apr. 5, 2010).

The two cases in this consolidated appeal arise from unrelated automobile negligence actions presenting a common procedural background birthing significant discovery disputes. In each case, the respective defendants designated, in pre-trial discovery, Dr. Joel Falik, M.D. (“Dr. Falik” or “Appellant”), a neurosurgeon, as a non-treating medical expert witness. The plaintiffs in each case each noted two-fold depositions of Dr. Falik: a “records deposition duces tecum” to be followed at a later date by a testimonial deposition. The notices of records deposition duces tecum requested the physician to produce certain documents regarding his past services as a medical forensic expert witness. Dr. Falik filed motions for protective orders. The trial courts in each case issued orders directing Dr. Falik to produce at least some of the records sought. Dr. Falik sought immediate appellate review in both cases.

. . . . II. Discovery of a Non-Treating Medical Expert’s Financial Records

Obviously, a party has a strong interest in the fact-finder’s assessment of the credibility of its expert witnesses. For the opposing party it is equally important to have the ability to search for legitimate evidence to impeach the credibility of those witnesses. Bias is one method of impeachment and “[i]t is well established that the bias, hostility or motives of a witness are relevant and proper subjects for impeachment.” Pantazes v. State, 376 Md. 661, 692, 831 A.2d 432, 450 (2003). See also Md. Rule 5-616(a)(4) (“The credibility of a witness may be attacked through questions asked of the witness, including questions that are directed at . . . [p]roving that the witness is biased, prejudiced, interested in the outcome of the proceeding, or has a motive to testify falsely.”). “Bias describes ‘the relationship between a party and a witness which might lead the witness to slant, unconsciously or otherwise, his testimony in favor of or against a party.’” Pantazes, 376 Md. at 692, 831 A.2d at 450 (quoting United States v. Abel, 469 U.S. 45, 52, 105 S.Ct. 465, 469, 83 L. Ed. 2d 450, 457 (1984)). It is well established that the fact that an expert witness is being paid to testify may bear on his or her credibility and may be revealed through cross-examination. Goldberg v. Boone, 396 Md. 94, 116, 912 A.2d 698, 711-12 (2006); Wrobleski v. de Lara, 353 Md. 509, 518, 727 A.2d 930, 934 (1999); Mezzanote Constr. Co. v. Gibons, 219 Md. 178, 181, 148 A.2d 399, 401-02 (1959). Thus, “an expert witness may be questioned on cross-examination about compensation received for testifying, as well as about the expert’s history of employment as an expert witness, in order to reveal bias or interest in the outcome of the proceeding.” Goldberg, 396 Md. at 116, 912 A.2d at 710-11.

“Expert opinion testimony can be powerful evidence.” Wrobleski, 353 Md. at 517, 727 A.2d at 933. An expert’s testimony “can have a compelling effect [on] a jury.” Id. “That is why, especially with expert witnesses, ‘wide latitude must be given a cross-examiner in exploring a witness’s bias or motivation in testifying,’ [and,] in particular, ‘the cross-examiner must be given latitude to cross-examine a witness concerning any bias or interest the witness may have that would lead the witness to shade his testimony, whether, consciously or not, in favor of or against a party.’” Id. (quoting Ware v. State, 348 Md. 19, 67, 702 A.2d 699, 722 (1997)).

. . . . Several courts have considered the issue of whether a trial court may compel an expert witness to produce potentially relevant income-stream financial records at the request of an opposing party. Although the courts and commentators may disagree on the outcome, many agree that the evidence may be relevant to the expert witness’s bias. See e.g., Sullivan v. Metro North R.R. Co., 2007 U.S. Dist. LEXIS 88938, at *4 (D. Conn. 3 Dec. 2007) (“There is no question that the information sought by Sullivan is relevant to bias impeachment, and therefore, falls within the scope of permissible discovery . . . .”); Behler v. Hanlon, 199 F.R.D. 553, 561 (D. Md. 2001) (“[N]o intellectually honest argument can be made that the information sought by plaintiff regarding [the expert’s] activities as a defense expert witness

. . . . The Pennsylvania Supreme Court, citing our Wrobleski, held that a party could obtain “supplemental discovery related to potential favoritism of a non-party expert witness retained for trial preparation” if there are “reasonable grounds to believe that the witness may have entered the professional witness category. In other words, 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.” 905 A.2d at 494-95. The court determined that the trial court did not abuse its discretion when it authorized discovery of the expert’s financial records. Id. at 495. The court was sympathetic, however, to the expert’s contention that it was burdensome to find and produce the financial information sought. Therefore, the court determined “that the appropriate entry point, upon the showing of cause, is a deposition by written interrogatories . . . .” Id. Through this, the court opined, the proponent of the discovery could inquire into, among other areas of possible bias, “the approximate amount of income each year, for up to the past three years, garnered from the performance of such services.” Id.

At that point, further discovery, such as obtaining financial records, might be warranted “if[,] [for example,] there is a strong showing that the witness has been evasive or untruthful in the written discovery.” Id. at 496. See also Behler, 199 F.R.D. at 562 (“[T]here is no need for the expert to have to produce his or her tax returns, if the party seeking the discovery has accurate information regarding the percentage of income earned as an expert.”); Am. Family Mut. Ins. Co. v. Grant, 217 P.3d 1212, 1220 (Ariz. Ct. App. 2009) (“[I]f an expert is uncooperative or untruthful in responding to less demanding discovery requests, a trial court has discretion to permit more comprehensive discovery.”); Allen v. Superior Court of Contra Costa County, 198 Cal. Rptr. 737, 741 (Cal. Ct. App. 1984) (holding that the trial court abused its discretion when it failed to require a less intrusive method of discovery); Elkins v. Syken, 672 So.2d 517, 521-22 (Fla. 1996) (adopting the intermediate appellate court’s holding that “the production of business records, files, form 1099’s may be only produced upon the most unusual or compelling circumstances . . . .”); Primm v. Isaac, 127 S.W.3d 630, 639 (Ky. 2002) (quoting Elkins, 672 So.2d at 521) (“If, after taking the deposition, a party can demonstrate that additional information is necessary to undertake reasonable bias impeachment, it may seek leave of court to take additional discovery. Further, should the trial court determine that the witness has not provided complete and unevasive answers to the deposition questions, or ‘has falsified, misrepresented, or obfuscated the required data, the aggrieved party may move to exclude the witness from testifying or move to strike the witness’s testimony . . . .”); State ex rel Creighton v. Jackson, 879 S.W.2d 639, 643-44 (Mo. Ct. App. 1994) (holding that the trial court did not abuse its discretion in permitting the discovery of the expert’s financial records where the party seeking discovery presented the trial court with evidence that in an unrelated deposition, the expert witness was unable to estimate his annual earnings from litigation activities). But see Ex Parte Morris, 530 So.2d 785, 789 (Ala. 1988) (holding that the prejudice to the non-party expert substantially outweighed the “incremental value that such information would provide respondent for purposes of showing bias . . . .”).

Turning to the orders issued in the present cases, we conclude that the trial court in Holthus followed thoughtfully our guidance in Wrobleski to allow only a controlled inquiry into whether a witness offered as an expert earns a significant portion or amount of income from applying his or her expertise in a forensic nature and is thus in the nature of a “professional witness.” Although the Circuit Court for Montgomery County ordered Dr. Falik to produce portions of his tax returns and related 1099 forms, it tailored the scope of the order to those portions which referenced any payment in connection with medical legal services and to a narrow sweep of contemporary time, the two years prior to the inquiry. Similarly, the ordered production of 1099 forms was limited in scope to the proffered expert’s services as an expert witness or for work done at the request of the defendant’s insurance carrier, State Farm Insurance Company. As noted above, the trial court’s order also contained very specific confidentiality provisions to ensure that the information would not be disseminated to anyone beyond those individuals mentioned in the order. The document production ordered cannot be characterized fairly as a “wholesale rummaging” through Dr. Falik’s personal finances and financial records.

. . . . We are not unsympathetic to Dr. Falik’s concern that the discovery of the documents at issue in the present case may be seem to him to be an unwarranted invasion into his privacy. As previously noted, our decision here is the result of balancing a party’s need to discover reliable and relevant information in order to try properly its case and the witness’s expectation of privacy. We are confident, however, that leaving the implementation of our decision in the first instance with the sound discretion of the trial courts to control tightly the inquiry (with attendant confidentiality restrictions) will keep these sensitive records from being disseminated publicly. We note that attorneys, as officers of the court, have a duty to keep such records private, unless a court orders otherwise. See Maryland Rule of Professional Conduct 3.4(c) (“A lawyer shall not . . . knowingly disobey an obligation under the rules of the tribunal except for an open refusal based on an assertion that no valid obligation exists.”). We acknowledge also Dr. Falik’s argument that our holding in this regard might create a chilling effect on the willingness of qualified professionals to serve as expert witnesses in litigation-related contexts. Any concern we might share in that regard, however, is over-balanced by the need to create a context for effective cross-examination. Moreover, we are confident that a trial court’s tight control over the process will restore to qualified professionals the confidence needed to encourage them to testify.