Writing a Forensic Engineering Expert Witness Report – Best Practices

Expert Institute Expert

Written by
— Updated on August 5, 2021

Forensic Engineering ExpertForensic engineering projects are often litigious in which different parties seek to collect or avoid damages based upon technical allegations. Such projects will often include the production of reports by the engineering expert witness at the completion of an investigation. Such a report is typically written and likely to be distributed to the various interested parties. This paper briefly describes the essential features of these reports. While the emphasis is placed upon the written report, the recommendations can equally pertain to verbal reports.

Purpose of the report

The primary objective of a forensic engineering report is typically to present defensible conclusions addressing concerns of a technical nature. These must be presented in a manner which is readily understandable to those who need to make use of these conclusions. The audience may therefore be other technical experts but likely include non-technical individuals. Where a report may be used in litigation, the likely recipients will be non-technical individuals. These may be attorneys or adjusters, and may ultimately be the trier of fact, such as a judge, jury members, or arbitrator(s).

Regardless of the thoroughness of any investigation or clarity of findings, the results and supporting arguments must be readily understood by the intended audience. The report may be the only opportunity to present the findings of the investigation. It may encompass the whole of any permitted testimony. Therefore, if details are not included, or the argument presented unintelligible, then, regardless of the soundness of the conclusions, the opinions presented may be rejected or at best misunderstood. This can have serious financial and legal consequences.


Style is not a technical argument and can therefore vary from author to author without detriment to the technical content. However, the choice of style may affect both the perceived credibility of the author as well as the reader’s ability to comprehend the text. Due cognizance should be given the intended audience of the report to maximize comprehension and credibility.

One obvious choice of style is that between using the active (“I”) or passive (third person) voice. While the passive voice has traditionally been used as it appears more dispassionate and therefore less prone to bias, the active voice provides a more direct and personal association between the author and the report contents.

Another question of style is flow of the report.  A report should read logically from beginning to end. Typically, information provided precedes observations, observations precede analyses, and analyses precede conclusions. Opinions will form naturally in the reader’s mind when facts are presented and explained in a logical flow. This approach also forces a discipline that typically enhances the work presented.

Regardless of the choice of style, spelling and grammar matter. These reflect, rightly or wrongly, on the education and training of the author, and the due diligence of the investigation.

Junk Science – Frye, Daubert, Kumho Tire and the Federal Rules of Evidence

Basic issues in acceptance of any report conclusions include provision of adequate documentation of statements, use of accepted references, valid sources of information and acceptable logic. In all instances the report should clearly differentiate direct observation from assumption or third party information and fact from professional opinion.

The courts have attempted to provide a methodology to differentiate junk science from valid scientific and technical arguments. The landmark cases include Frye v.United States. 293 F. 1013 (D.C. Cir 1923), Daubert v. Merrell Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993), and Kumho Tire Co. v. Carmichael, 526 U.S. 137, 119 S. Ct. 1167 (1999). These have been applied in federal courts and rules arising from these cases are embodied in the Federal Rules of Evidence and, with some variation, to many state legal systems.

The Federal Rules of Evidence which apply to expert witness testimony are contained in Chapter 7. Section 702, on Expert Testimony, is reproduced below:

Rule 702. Testimony by Expert Witnesses

A witness who is qualified as an expert by knowledge, skill, experience, training, or education may testify in the form of an opinion or otherwise if: (a) the expert’s scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue; (b) the testimony is based on sufficient facts or data; (c) the testimony is the product of reliable principles and methods; and (d) the expert has reliably applied the principles and methods to the facts of the case.

If the “trier of fact” cannot understand the expert witness, the expert has failed in their objectives. It is therefore important to clearly define terms which may be ambiguous or simply not understood. Terms such as “many”, “okay”, “adequate” can be interpreted in a multiplicity of ways.  Technical terms should also be clearly defined in the body of the report. Jargon should be avoided, or carefully identified [e.g., steel reinforcement bars (“rebar”)]. Those most interested in the findings of the investigation are rarely technically knowledgeable. Where possible, illustrations should be used to assist in explaining technical concepts; e.g., load path.

In an ideal world, an expert witness report should be able to stand on its own and anyone provided with the same information should be able to reach the same conclusions. Sufficient facts or data must therefore be provided within the report and the principles and methods on which these data and facts are used to reach conclusions must be acceptable, reliable and relevant to the argument. Whenever the report fails in this regard an accusation of junk science may be made.

Looking for an expert in Forensic Engineering? Click here to find qualified experts for report writing, deposition, and trial testimony.

Use of industry accepted references should be used whenever possible to substantiate statements. Although there may be circumstances where test procedures need to be developed for a specific problem, test protocols, where possible, should also be referenced to acceptable sources. Test procedures prepared under ANSI protocols are typically considered acceptable in the US court system. Where no such standard exists, it may be possible to resort to other sources, such as the International Organization for Standardization (ISO); however, use of international standards which are not recognized in the United States may result in rejection by the court.

The hallmarks of the American National Standards process include (taken from the ANSI website):

  1. consensus on a proposed standard by a group or “consensus body” that includes representatives from materially affected and interested parties
  2. broad-based public review and comment on draft standards
  3. consideration of and response to comments submitted by voting members of the relevant consensus body and by public review commenters
  4. incorporation of approved changes into a draft standard
  5. right to appeal by any participant that believes that due process principles were not sufficiently respected during the standards development in accordance with the ANSI-accredited procedures of the standards developer.

It is important to note that, while an ANSI approved test standard may exist, it may still not be applicable to the issue being addressed.

In addition to test standards, standards may also related to design, installation, manufacture, inspection or other activity. Such industry “standards” are also typically prepared under the aegis of ANSI. Where this is not done, the document may be considered a guideline, recommendation. As for test standards, where an ANSI approved design standard may exist, it may still remain inapplicable to the issue being addressed.

With regard to attributing information to others’ statements, care needs to be taken to clearly differentiate a direct quote from a paraphrased statement. Whether quoted or not, it needs to be clearly stated if statements arise from depositions, witness statements, other reports or were heard directly. Source, date and reference location should all be provided, where this information is available. Where witness statements are quoted, the interviewer should be identified, including name and affiliation. Where appropriate, the interest represented by the interviewer; i.e., the client or agency, should be named. Use of standard footnote citation and bibliography protocols will usually suffice. Although clients, particularly attorneys, may have particular preferences with regard to the method of giving attribution.

ASTM test standards typically contain statements regarding precision and bias in the test results. Tests are designed to be repeatable, such that independent researchers will obtain the same results following the stated protocols. Any tests or investigations which are referenced within the report should be repeatable, to the extent that the information or test materials upon which that report is based are still available.

Claiming expertise does not render an opinion valid without a sound scientific basis. Testimony based solely on experience and expertise is generally invalid.

Report Organization

Per the Guidelines For Forensic Engineering Practice Second Edition, Prepared by Forensic Practices Committee Technical Council on Forensic Engineering of the American Society of Civil Engineers, a report contains five basic elements: introductory information, description of the issues, information supplied, investigation results and conclusions. The following represents the standard sections listed in the Guidelines which may be contained in a report prepared as part of a forensic engineering investigation. It is noted that the order is suggested only, as the style, complexity of issues and volume of material will all affect the final layout of the report.

  1. Cover Page
  2. Title Page
  3. Table of Contents
  4. Executive Summary
  5. Introduction / Background
  6. Scope of Work
  7. Organization Chart
  8. Approach
  9. List of Documents
  10. Other Information (supplied or obtained)
  11. Site Visits
  12. Description of the Site/Building
  13. Review of Documents
  14. Site Observations
  15. Analyses
  16. Test results
  17. External Reports
  18. Discussion
  19. Conclusions
  20. Recommendations
  21. Disclaimer
  22. Signature
  23. Photographs, Charts, Graphs and Figures (if not included in the body of the report)
  24. Appendices

Most reports do not require all sections to be included, and, where clarity is not lost sections may also be combined. Additional sections may also be added as required. Where lists, photographs, reference materials, source documents and other backup materials is needed, these are typically included within the Appendices.

Sections which are typically always included are a cover page, executive summary (or “summary”), Introduction / Background, Scope of Work, List of Documents, Site Visits, Description of the Site/Building, Review of Documents, Site Observations, Discussion, Conclusions, Disclaimer, Signature.

Where no site visits have been made, this should be noted.

Every report should be uniquely titled and every page should contain a unique identifier, including the report title, date of issue and company name. Interim reports and drafts should be appropriately identified as such and dated individually.

As it is typical for most investigations to be limited, whether due to time, scope, budget, program or other cause, no investigation can be considered to be complete. Additional information, site visits, tests or other information may always be forthcoming. It is therefore typical to include a general disclaimer in any forensic engineering report incorporating the right to amend the report to the extent dictated by receipt of new information, from whatever source. Many of these limitations will be described or alluded to under the scope of work, list of documents received, site visits undertaken and introduction. Where additional limitations may be present, it is prudent to make these clear.

The objective and permitted use of the report, if not already described in the scope of work being provided, is recommended to be included. The “National Practice Guidelines for the Preparation of Structural Engineering Reports for Buildings”, CASE 962-A, published by the Council of American Structural Engineers, contains several possible disclaimer statements, in addition to information on other report types.

It is typically required for the author to sign the report. The author is also typically the individual in control of the forensic investigation and, when needed, the expert witness. The contents of the report must represent the work and the opinion the author, although that does not preclude contributions by others. However, any contribution must be limited to the provision of information, whether through analysis, site assistance, testing or other means.

In complex cases, one expert needs to be able to incorporate the expertise of others on specific subtopics. As such, he needs to be able to independently evaluate the analysis and conclusions of the subtopic expert and incorporate them if sound. A structural engineer can for example rely and incorporate the findings of a wind tunnel expert or of a computational mechanics expert. Regardless, this cannot and should not include formulation of an opinion for simple adoption by the author. To this purpose many forensic engineers affix their professional seal to the report. This may also be required in some jurisdictions.

The Role of Peer Review

No matter how careful, errors may be present in a report, particularly where the issues are complex. Additionally, spelling and grammatical errors, as well as general formatting issues, may have been missed which detract from the professionalism of the overall presentation to the detriment of a perceived credibility on the part of the reader. Further, lack of clarity (as written) in the investigation approach, a failure to define technical terms and potential errors in logic may be present.

Peer review is therefore an essential feature in the engineering community, whether for forensic or other reports. It allows the individual to check their assumptions, calculations, analysis, designs and logic in addition to grammar, spelling and punctuation.

It should also be noted that peer reviews are not limited to review by a single individual. In the simple example of separate technical and spelling/grammar reviews, a minimum of two reviewers would be required.

It is often, but not necessarily, the case that the reviewing engineer may have more experience certain subject matters than the expert engineer of record. For example, in complex failures involving multiple disciplines, a specialist may be needed to supplement the breadth of knowledge for a complex failure, that specialist has been retained to the greater knowledge in a specific topic. In larger organizations, the reviewing engineering may be senior to the designated expert engineer. This does not preclude the expert engineer from acting in that capacity. The expert engineer will ultimately be the individual with the fullest knowledge of the issues of the particular project.

Forensic engineering reports are the essential work product of the majority of forensic engineering investigations. In many instances the report may be the only means for communicating the details and conclusions of any investigation and for imparting the opinions of an expert to others. It is therefore necessary for the report to be clear, concise, logical, defensible and understandable by those who need to rely upon its contents. Failure to do so can result in significant harm to others both financial and legal. Success will achieve a more rapid and just outcome at significantly less cost to all.

This post was written by a forensic engineering professional with over 35 years experience in forensic engineering, failure investigation, mitigation, response, repair and rehabilitation. 

Leave a Reply

Your email address will not be published.

I am an