Serving as an expert witness during a lawsuit often extends beyond writing an initial report or giving testimony at deposition or trial. Expert witnesses may also be asked to evaluate the reports generated by an opposing party’s expert witness and to raise issues they find in that report. The resulting document is known as a rebuttal report.
Updated on August 17, 2022
A rebuttal report analyzes and refutes the positions the opposing expert takes in their expert witness report. A good rebuttal report will establish a foundation for questioning the expert’s credibility. Through this foundation developed and the analysis presented, the strongest rebuttal reports also demonstrate that the rebutting author took the best route available for understanding the issues in the case.
When a rebuttal report does double duty in this way, it not only exposes weaknesses in the opposing expert’s conclusions but also reaffirms the strength of the conclusions reached by the rebuttal’s writer in their own expert witness report.
The first step in any strong rebuttal is to thoroughly understand the arguments, methods, and conclusions presented by the opposing party.
Start by reading the report to familiarize yourself with its layout, contents, and conclusions. Then, reread it, focusing on areas of weakness within the methods, analysis, and conclusions. Many expert witnesses perform this step with a pen or highlighter handy so that they can make notes for themselves.
While reading critically, also note any places where the opposing expert’s report agrees with your own work or with the position taken on the side of the case to which you are contributing. Identifying areas of agreement can help you focus the rebuttal on the areas of disagreement. Establishing agreement can also help build your own credibility as a rebuttal source because it demonstrates that you are able to acknowledge similarities rather than merely reacting from bias.
Once a clear understanding of the opposing expert’s assumptions, methods, analysis, and conclusions has been established, it may help to attempt to recreate the opposing expert’s analysis. Such a recreation can reveal specific flaws in the expert’s approach. It can also reveal how that flawed approach led to flawed conclusions.
Not all cases will lend themselves to a recreation of an opposing expert’s analysis. Time and resources may be scarce, for example, or the opposing expert’s approach may depend on factors that can’t easily be recreated. In these cases, an expert may nevertheless benefit from walking through each step of the analysis, imagining how it would have been carried out in practice, and looking for flaws.
During this process, stay alert both for explicit assumptions and implicit assumptions. Explicit assumptions are typically stated outright—they’re known to the opposing expert and may be factored in as part of the conclusion. Implicit assumptions, however, may not be stated outright. in fact, the opposing expert may not even be aware of them but they nevertheless affect the conclusion.
Addressing both explicit and implicit assumptions can help an expert write a clearer rebuttal, especially if any assumption affects the conclusions reached.
The rebuttal report should address a number of areas. First, as noted above, summarize the issues or topics on which your own work agrees with that of the opposing expert. Create common ground as a way to build credibility and direct the reader’s attention toward key areas of disagreement.
Identify any clear, objective errors, such as errors of fact or mistakes in calculation. Such errors do not appear in every expert witness report. But when they do, they provide a clear, easily-evaluated starting point for discussing weaknesses in the report.
Next, focus on any contradictions within the report. Contradictions and inconsistencies often indicate flaws in methodology, analysis, or resulting conclusions. Examples include inconsistent use of inputs, switching methodologies, or citing and quoting sources selectively or out of context.
As you identify issues, provide alternatives where possible. For example, if a mathematical equation was solved incorrectly, provide the correct solution, and explain how the correct solution affects the opposing expert’s conclusions. If the opposing expert quotes a source out of context, provide the context and explain its effects on the expert’s report and the case as a whole.
Finally, avoid contradicting your own work or the client’s position in your rebuttal report. Ideally, the rebuttal will serve as further evidence that your own work is correct and the client’s position is justified.
Rebuttal reports require experts to balance multiple perspectives at once. They also require experts to think critically about their own and an opposing position simultaneously. This exercise in critical thinking, done well, can have a profound effect on a client’s case.
About the author
Dani Alexis Ryskamp, J.D.
Dani Alexis Ryskamp, J.D., is a multifaceted legal professional with a background in insurance defense, personal injury, and medical malpractice law. She has garnered valuable experience through internships in criminal defense, enhancing her understanding of various legal sectors.
A key part of her legal journey includes serving as the Executive Note Editor of the Michigan Telecommunications and Technology Law Review. Dani graduated with a J.D. from the University of Michigan Law School in 2007, after completing her B.A. in English, summa cum laude, in 2004. She is a member of the Michigan State Bar and the American Bar Association, reflecting her deep commitment to the legal profession.
Currently, Dani Alexis has channeled her legal expertise into a successful career as a freelance writer and book critic, primarily focusing on the legal and literary markets. Her writing portfolio includes articles on diverse topics such as landmark settlements in medical negligence cases, jury awards in personal injury lawsuits, and analyses of legal trial tactics. Her work not only showcases her legal acumen but also her ability to communicate complex legal issues effectively to a wider audience. Dani's blend of legal practice experience and her prowess in legal writing positions her uniquely in the intersection of law and literature.
