Expert Witness Disclosures:
How to Comply and Avoid Exclusion

Bench & Bar of Minnesota
Vol. 65, No. 4 | April 2008

Who must be considered an expert? Must the expert submit a report? What information is discoverable from the expert? Knowing appropriate strategies for handling expert witness testimony in federal court can not only provide protection against exclusion, but should reduce disputes and control litigation costs.

By Courtland C. Merrill

Before expert testimony is evaluated under the standards of Daubert or heard by a jury, the party offering the expert must first comply with specific disclosure requirements during discovery. Failure to sufficiently comply with expert disclosure requirements under the Federal Rules of Civil Procedure can result in exclusion of the expert’s opinions, and even dismissal when expert testimony is necessary to support a claim. [1] While expert disclosures have been a part of civil litigation for years, issues concerning who must be identified as an expert, which experts must submit reports, and what information is discoverable from experts, continue to arise over the course of litigation and create confusion. Effective strategies should be taken well before trial to prevent inadequate disclosure and avoid exclusion.

Who Is an Expert?

A party must disclose, without awaiting a discovery request, "the identity of any witness it may use at trial to present evidence under Federal Rule of Evidence 702, 703, or 705." [2] The line between expert testimony and lay opinion testimony is not easy to draw. Pretrial scheduling orders typically require identification of testifying experts months in advance of trial. Therefore, careful practitioners should consider—before the required date to identify experts in the pretrial order—whether the opinions of any fact witnesses constitute expert testimony.

To determine whether proposed testimony is expert testimony, one turns to Rule 702 of the Federal Rules of Evidence, which states that a witness who is "qualified as an expert by knowledge, skill, experience, training, or education" may testify to "scientific, technical or other specialized knowledge" in the form of opinion or otherwise where such knowledge "will assist the trier of fact to understand the evidence or to determine a fact in issue." [3] The inquiry does not stop with Rule 702. Equally important is Federal Rule of Evidence 701 which limits the opinions of lay witnesses. Rule 701 provides: "If the witness is not testifying as an expert, the witness’ testimony in the form of opinions or inferences is limited to those opinions … based on the perception of the witness …[and …] not based on scientific, technical, or other specialized knowledge within the scope of Rule 702." [4]

Rule 701 is intended to prohibit parties from evading the expert disclosure requirements by offering what amounts to expert testimony from lay witnesses, such as the parties or their employees. [5] Under Rule 701, lay testimony may not "provide specialized explanations or interpretations that an untrained lay person could not make if perceiving the same acts or events." [6] Rule 701 "does not distinguish between expert and lay witnesses, but rather between expert and lay testimony." [7] Thus, "any part of a witness’ testimony that is based upon scientific, technical or other specialized knowledge within the scope of Rule 702 is governed by the standards of Rule 702 and the corresponding disclosure requirements of the Civil … Rules." [8]

Courts can and will exclude lay opinions that fail to comply with Rule 701. In Blandin Paper Co. v. J&J Industrial Sales, Inc., Judge Montgomery prohibited fact witnesses not identified as experts from opining whether a cleaning solvent containing hydrochloric acid damaged machinery. [9] Similarly, in Medtronic, Inc. v. Boston Scientific Corp., Judge Kyle concluded that testimony by employees of a party, concerning whether certain physical properties were present in "shape memory alloys" used in coronary stents, was in fact expert testimony. [10] Judge Kyle determined that the employees’ testimony fell within the scope of Rule 702 because it relied on inferences gained from specialized training and that could not be perceived by the five senses.

Lay testimony does not, however, become expert testimony simply as a result of the particularized knowledge that the witness has by virtue of holding a position in the business. [11] Most courts have permitted the owner or officer of a business to testify to the value or projected profits of the business without the necessity of qualifying the witness as an accountant, appraiser, or similar expert. [12] A fact witness may testify to personal observations which relate to the subject matter of litigation, or knowledge gained from industry experience or review of records prepared in the ordinary course of business; a fact witness may neither respond to hypothetical facts nor review documents that are extraneous to the witness’ personal knowledge merely to form opinion testimony. [13]

Given the fuzzy boundary between lay and expert testimony, one strategy to prevent exclusion is to identify any fact witness as an expert if there is any risk the witness’ testimony might be deemed expert testimony. Courts that have excluded lay opinion testimony have indicated that the testimony would have been permissible had the witness been timely identified as an expert. [14] Indeed, the best expert may very well be your client or one of its employees. Courts routinely permit expert testimony by a party, employee, or other with interest in the outcome of the litigation where the person has been identified as an expert and has complied with disclosure requirements. Witnesses with a pecuniary interest in the outcome of the case may serve as experts. [15] A witness’ pecuniary interest goes to the probative weight of testimony, not its admissibility. Moreover, you can avoid the high cost of an outside expert by using your own client or an employee as an expert. You may be better off with your client as an expert—one who believes in the case and who will be very credible, if well prepared. [16]

Reporting Requirements

Federal Rule of Civil Procedure 26(a)(2)(B) requires an expert "retained or specially employed to provide expert testimony … or one whose duties as the party’s employee regularly involve giving expert testimony" to submit a written report which "must contain … a complete statement of all opinions the witness will express and the basis and reasons for them," among other things. [17] Rule 26(a)(2)(B) contemplates two types of experts. One type of expert is the person whose opinions may be presented at trial but who is not required to submit a report. This first type includes experts whose opinions are based on firsthand knowledge and who do not regularly provide testimony. [18] For example, a treating physician who has rendered an opinion based on firsthand knowledge of a patient is generally not required to submit a report because he is not considered "retained or specially employed" to provide testimony. [19] The second type of expert is one whose opinions may be presented at trial, and who is required to submit a report because he was retained or specially employed for the purpose of providing expert testimony. This second type of expert may provide testimony based on secondhand information to which she has no personal knowledge.

There is a split in authorities concerning whether employee experts must submit written reports. Some courts have found that employee experts are exempt from the written report requirement when they are not specially employed to provide expert testimony and do not regularly testify as experts. [20] These courts rely on the logic that if the drafters of Rule 26(a)(2) (B) had intended to impose an obligation on all employee experts, they could have and would have done so. Other courts have declined to recognize an exemption to the report requirement for employee experts. [21] This view finds that an exemption from the written report requirement for employee experts would create a distinction at odds with the purpose of Rule 26(a)(2) (B), which is to promote full disclosure of expert information.

Minnesota federal courts have been less than uniform as to whether employee experts must submit reports. In 3M v. Signtech USA, Ltd., Magistrate Lebedoff ruled that employees testifying as "fact or hybrid fact/ expert witnesses" were "retained or specially employed" for purposes of Rule 26(a)(2)(B) and were required to submit reports. [22] However, in Duluth Lighthouse for the Blind v. C.G. Bretting Mfg. Co., Magistrate Erickson was "not persuaded that the [c]ourt, in Signtech, reached the correct result." [23] Magistrate Erickson concluded that a plain reading of Rule 26(a)(2)(B) excludes employee experts not specially retained to testify and who do not routinely perform that function. In a subsequent unpublished case, Judge Kyle concluded that "the distinction drawn by the magistrate judge in [Signtech] between ‘fact or hybrid fact/expert witnesses’ and ‘expert witnesses’ appears to run counter to the evidentiary rule on expert testimony." [24] Judge Kyle nonetheless determined that when a corporation identifies an employee as an expert who does not normally provide expert testimony, that the employee has been "specially employed" and a report is required.

Given this lack of clarity, a practitioner relying on employee expert testimony may well consider voluntarily complying with the written report requirement. Agreeing to provide a report from an employee expert could provide an additional assurance against exclusion and avoid a costly dispute. In any event, courts may order submission of a report as a means of fulfilling the court’s own gatekeeper duties under Daubert, even when an expert is not automatically required to do so. [25]

How Much Detail?

In addition to opinions and bases, an expert report must contain the expert’s qualifications, all of the data or other information considered in forming the opinions, all summary or supporting exhibits, all publications authored in the preceding ten years, compensation the expert was paid, and a listing of all cases in which the expert gave prior deposition or trial testimony within the preceding four years. [26] The advisory committee notes state that the report must be "detailed and complete." [27] These notes also explain that the purpose of the report is to avoid the disclosure of "sketchy and vague" expert information. [28]

Case law instructs that a "complete and detailed" report contains the substance of the direct examination sufficient to qualify the witness as an expert and establish the admissibility of the expert’s opinion without the need for additional testimony or information. [29] Reports have been excluded where the opinions were unsupported except by general reference to records or omitted qualifications, compensation, and previous testimony. [30]

Compiling an expert’s qualifications, publications and prior testimony are things that should be done when the expert is engaged. If a potential expert has difficulty providing this information, alarm bells should sound as to whether the expert is someone that you want to rely on at trial.

Writing the Report

If required, the report must be "prepared and signed by the witness." [31] The advisory committee notes say that this requirement "does not preclude counsel from providing assistance to experts in preparing the report." [32] Counsel may assist in the preparation of an expert’s report, so long as the report is written in a manner that reflects the expert’s opinions and is signed by the expert.

Several courts have addressed the permissible amount of attorney involvement in drafting an expert report. These courts conclude that as long as the substance of the opinions is from the expert, the attorney’s involvement in the written expression of those opinions does not make them inadmissible, but caution that a report drafted entirely by counsel without prior substantive input from an expert would read the word "prepared" completely out of the rule. [33] Most attempts to exclude expert testimony on the grounds that the report was "ghost-written" by counsel prove unsuccessful. [34] Courts have rejected a formalistic approach which would "require that the expert be the person who actually puts pen to paper (or fingers to keyboard)." [35]

In a perfect world, all experts will prepare their own reports that comply with each element of Rule 26(a)(2)(B) and Daubert, with little assistance from counsel. This isn’t reality. Many experts will need significant assistance from counsel to prepare their report. The advisory committee notes identify an automobile mechanic as an example of an expert who might potentially need assistance in preparing a report. [36] Disputes over who authored an expert report usually uncover little evidence of value, detract from the merits, and unnecessarily increase costs.

Submitting & Supplementing

Absent a stipulation or specific date ordered by the court (as trial courts commonly do), the report required by Rule 26(a)(2)(B) must be submitted 90 days before trial or, if intended solely to rebut another party’s proposed expert testimony, within 30 days after the other party’s disclosure. [37] A rebuttal report is limited to explaining or disproving evidence of the adverse party; it is not an opportunity to correct oversights in the party’s case-inchief. [38] A rebuttal report should not be excluded on the grounds that the expert could have included the information in the original report so long as the new information is limited in scope to matters raised by the opposing expert’s disclosure. [39]

Parties must supplement the disclosures made in the report "when required under Rule 26(e)." [40] Rule 26(e) has two requirements applicable to experts. First, a party must timely supplement or correct if the party "learns that in some material respect the disclosure or response is incomplete or incorrect, and if the additional or corrective information has not otherwise been made known to the other parties during the discovery process or in writing." [41] Second, Rule 26(e)(2) requires the expert to supplement the information in his report before the date the party’s pretrial disclosures are due under Rule 26(a)(3). [42]

Expert Discovery

Federal Rule of Civil Procedure 26(b)(4) governs expert discovery. The scope of discovery depends on whether the expert will testify at trial. The work product of consulting experts is generally undiscoverable except upon showing of exceptional circumstances. [43] Consequently, all experts should be retained, at the outset of the engagement, as consulting experts. Unless and until you are required to designate testifying experts pursuant to Rule 26 (a)(2)(A) or (B) (or the pretrial order), you don’t know with certainty whether you will need a testifying expert or, if you do, whether the experts initially retained will ultimately be the right ones for trial, in light of the evolution of the case through discovery and motion practice. [44]

Testifying experts may be deposed regardless of whether or not they submit a report. [45] If an expert must submit a report, the deposition shall not be conducted until after the report is submitted. [46]

Communications with testifying experts are generally not privileged. Release of materials to a testifying expert waives a work product claim. In In re Pioneer Hi-Bred Intern., Inc., the Federal Circuit concluded that under 8th Circuit law, documents and information disclosed to a testifying expert in connection with the expert’s testimony are discoverable by the opposing party, whether or not the expert relies on the documents and information in preparing her report. [47] In the advisory committee notes, the drafters observe: "litigants should no longer be able to argue that materials furnished to their experts to be used in forming their opinions—whether or not ultimately relied upon by the expert—are privileged or otherwise protected from disclosure when such persons are testifying or being deposed."

While Rule 26(a)(2)(B) requires the disclosure of all materials considered by a party’s employee designated as a testifying expert regardless of attorneyclient or work-product privilege, the scope of such waiver does not extend to information and/or documents that an employee-expert may have considered in performing his general job duties but did not consider in connection with formulating the opinions expressed within the report. [48] Therefore, employees may serve as experts without waiving privilege concerning information unrelated to the opinions they intend to offer at trial.

Draft Reports

Draft reports are "information considered by the witness in forming the opinions," and, therefore, material that must be disclosed under Rule 26(a)(2) (B). Any drafts that are retained—whether by the expert or by counsel, and whether on paper or in electronic form—are potentially discoverable. Some courts have held that counsel have legal or ethical obligations not to destroy any drafts that the expert may transmit to them. [49]

Even if such drafts are discoverable, the discovery of drafts of expert reports rarely provides substantial benefits. One needs only to read the Trigon Ins. Co. v. United States case from the Eastern District of Virginia and wonder as to the amount of money spent on the extraneous dispute concerning draft reports. Thankfully, at least in the District of Minnesota, there appears to be a trend away from discovery of draft reports. The 2005 Patent Advisory Committee for the District of Minnesota, which made recommendations with respect to local rules for patent cases, made a specific recommendation to end wasteful motion practice regarding the discovery of draft reports. Those recommendations resulted in the District of Minnesota adopting local rules applicable to patents cases which encourage parties to agree in advance as to the discoverability of drafts of expert reports and provide that in the absence of agreement, drafts are not discoverable. [50] While these local rules apply only to patent cases, they provide a template that could be utilized in other complex cases as a way to avoid disputes over draft reports.


Most pitfalls concerning expert witness disclosures can be avoided by strategies such as identifying witnesses as experts when their testimony potentially falls within the scope of Rule 702, voluntarily submitting reports from employee-experts, compiling information required in an expert report at the beginning of the engagement, engaging experts as consultants until required to designate them as a testifying expert, and seeking agreement from opposing counsel at the beginning of the case regarding the scope of discovery. These and other strategies should not only provide protection against exclusion, but should reduce disputes and control litigation costs.


  1. Under Fed. R. Civ. P. 37(c)(1), if a party fails to disclose expert opinions or exhibits, the undisclosed matter is automatically excluded at trial, unless there is "substantial justification" for the failure or the "failure is harmless." See White v. Howmedica, Inc., 490 F.3d 1014, 1016 (8th Cir. 2007).
  2. Fed. R. Civ. P. 26(A)(2)(A).
  3. Fed. R. Evid. 702.
  4. Fed. R. Evid. 701.
  5. Fed. R. Evid. 701, Advisory Committee Note–2000 Amendment.
  6. United States v. Peoples, 250 F.3d 630, 641 (8th Cir. 2001); see also United States v. Shedlock, 62 F.3d 214, 219 (8th Cir. 1995); C.H. Robinson Worldwide, Inc. v. Ghiradelli Chocolate Co., No. 03-2978 (JRT/FLN), at *2 (D. Minn. 05/23/05).
  7. Fed. R. Evid. 701, Advisory Committee Notes–2000 Amendment.
  8. Id.
  9. Blandin Paper Co. v. J&J Industrial Sales, Inc., No. Civ.02-4858 ADM/ RLE, 2004 WL 1946388, at *3 (D. Minn. 09/02/04).
  10. Medtronic, Inc. v. Boston Scientific Corp., No. 99-1035 RHK/FLN, slip. op. at 50 (D. Minn. 08/08/02).
  11. Fed. R. Evid. 701, Advisory Committee Note–2000 Amendment.
  12. Id.; Bberco v. Metrix Co., 324 F.3d 955, 963 (8th Cir. 2003); Eckelkamp v. Beste, 315 F.3d 863, 872 (8th Cir. 2002).
  13. Hartzell Mfg., Inc. v. American Chemical Technologies, Inc., 899 F. Supp. 405, 409 (D. Minn. 1995).
  14. Freedom Wireless, Inc. v. Boston Communications Group, Inc., 369 F. Supp. 2d 155, 158 n. 1 (D. Mass. 2005).
  15. CardioVention, Inc. v. Medtronic, Inc., 483 F.Supp.2d 830, 847 (D. Minn. 2007).
  16. Hosteny, Joseph N., "Being Cheaper: Keeping Litigation Costs Down," Intellectual Property Today, January 2007 at 35.
  17. Fed. R. Civ. P. 26(a)(2)(B).
  18. Fed. R. Civ. P. 26(a)(2)(B), Advisory Committee Note–1993 Amendment.
  19. Id.
  20. Navajo Nation v. Norris, 189 F.R.D. 610, 613 (E.D. Wash. 1999); Bank of China v. NBM LLC, 359 F.3d 171, 182 n. 13 (2d Cir. 2004); Bowling v. Hasbro, Inc., No. 05-229S, 2006 WL 2345941, at *2 (D.R.I. 08/06).
  21. See, e.g., Dyson Tech. Ltd. v. Maytag Corp., 241 F.R.D. 247, 249 (D. Del. 2007); KW Plastics v. U.S. Can Co., 199 F.R.D. 687, 688 (M.D. Ala. 2000); Storage Technology Corp. v. Custom Hardware Engineering & Consulting, Ltd., No. 02-12102-RWZ, 2006 WL 1766434, *36 (D. Mass. 06/28/06); Day v. Consol. Rail Corp., No. 95 CIV 968 (PKL), 1996 WL 257654, at * 1-3 (S.D.N.Y. 05/15/96).
  22. 3M v. Signtech USA, Ltd., 177 F.R.D. 459, 461 (D. Minn. 1998) (Lebedoff, M.J.).
  23. Duluth Lighthouse for the Blind v. C.G. Bretting Mfg. Co., 199 F.R.D. 320, 325 (D. Minn. 2000) (Erickson, M.J.).
  24. Medtronic, Inc. v. Boston Scientific Corp., No. 99-1035 RHK/FLN, slip. op. at 49-52 (D. Minn. 08/08/02) (Kyle, J.) (citing KW Plastics v. U.S. Can Co. 199 F.R.D. 687, 690 (M.D. Ala. 2000)).
  25. Holder v. Gold Fields Mining Corp., No. 04-CV-0564-CV-PJC, 2007 WL 128224, at *4-5 (N.D. Okla. 01/11/07).
  26. Fed. R. Civ. P. 26(a)(2)(B).
  27. Fed. R. Civ. P. 26(a)(2)(B), Advisory Committee Notes–1993 Amendment.
  28. Id.
  29. Sylla-Sawdon v. Uniroyal Goodrich Tire Co., 47 F.3d 277, 283-84 (8th Cir. 1995).
  30. Campbell v. McMillin, 83 F. Supp. 2d 761, 764-65 (S.D. Miss. 2000).
  31. Fed. R. Civ. P. 26(a)(2)(B).
  32. Fed. R. Civ. P. 26(a)(2)(B), Advisory Committee Notes–1993 Amendments.
  33. See Trigon Ins. Co. v. United States, 204 F.R.D. 277, 291-95 (E.D. Va. 2001).
  34. Trigon Ins. Co., 204 F.R.D. at 291-95; Indiana Ins. Co. v. Hussey Seating Co., 176 F.R.D. 291, 292-93 (S.D.Ind.1997); but see In re Jackson National Life Insurance Company Premium Litigation, No. 96-MD-11222, 2000 WL 33654070 (W.D. Mich. 02/08/00).
  35. Crowley v. Chait, 322 F. Supp. 2d 530, 545 (D.N.J. 2004).
  36. Fed. R. Civ. P. 26(a)(2)(B), Advisory Committee Notes–1993 Amendments.
  37. Fed. R. Civ. P. 26(a)(2)(C).
  38. Crowley, 322 F. Supp. 2d at 551.
  39. Id.
  40. Fed. R. Civ. P. 26(a)(2)(D).
  41. Fed. R. Civ. P. 26(e)(1)(A), which applies to all Rule 26(a) disclosures, including expert disclosures under Rule 26(a)(2).
  42. Fed. R. Civ. P. 26(e)(2); see, e.g., EZ Dock, Inc. v. Schafer Sys., Inc., No. Civ.98-2364 (RHK/AJB), 2003 WL 1610781, at *10-11 (D. Minn. 03/08/03).
  43. Fed. R. Civ. P. 26(b)(4)(B)(ii).
  44. Joseph, Gregory P., "Engaging Experts," National Law Journal, 04/18/05 at 12.
  45. Fed. R. Civ. P. 26(b)(4)(B).
  46. Id.
  47. In re Pioneer Hi-Bred Intern., Inc., 238 F.3d 1370, 1375 (Fed. Cir. 2001).
  48. Dyson Tech., 241 F.R.D. at 251.
  49. Trigon Ins, 204 F.R.D. at 284.
  50. United States District Court District of Minnesota, 2005 Advisory Committee’s Note to LR 16.2 and Form 4 and 5

COURTLAND MERRILL is an attorney at the Minneapolis law firm of Anthony Ostlund Baer Louwagie & Ross P.A. He is a 2001 graduate of the University of North Dakota School of Law. His practice focuses on business litigation, including contract disputes, trade secret misappropriation, patent and copyright infringement, noncompete agreements, and employment disputes.