Fact witnesses at trial can only testify about facts they know from their own personal knowledge. But sometimes, a party needs to introduce evidence about general practices and customs in an industry, or about some fact that requires an opinion from an expert. To address that need, courts often allow experts to testify in court about the subject of their expertise.

One step in the process of introducing expert testimony is preparing reports by the expert that set forth the substance of their testimony. These reports often require a lot of work, both from the expert and from counsel.

Why should you read this post about expert reports?

You want to know why a lawyer would have any role in preparing a report on a subject about which they are not an expert.
You’re curious to see if a post about expert reports can be as boring as an expert report.
You want to start a career as a highly paid expert witness, which would be a fun job/premise for a procedural drama.

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Expert Reports Disclose the Substance of Testimony

Courts are naturally suspicious of expert witnesses for three reasons. First, one side chooses them and so that side may have been biased in selecting an expert that will provide favorable testimony. Second, the witness is paid by one side, so there is a chance that the expert will tailor their testimony to satisfy their paying client. And third, unlike fact witnesses, a court is generally unable to assess the credibility of an expert who testifies about a subject a lay person is unfamiliar with.

To address these concerns, experts are usually required to prepare a report that sets forth what they will testify about at deposition and at trial. You can view a sample expert report here and another here. The report itself is often not evidence, but just a way for opposing counsel to know what the expert is going to say so that they can challenge the expert’s qualifications or conclusions. To ensure that the reports fully disclose the expert’s testimony, a court will often prohibit an expert from testifying about subjects that are not in her report.

Expert reports not only discuss the expert’s conclusions, but the materials upon which they relied to make their conclusions and the process they followed to reach their conclusions. They also often state the qualifications of the expert.

A good expert report is designed to withstand a challenge by opposing counsel to the expert’s testimony. It should show that the expert is qualified to opine on the subject matter, has based her conclusions on reliable and admissible evidence, and used generally accepted principles to reach her conclusion.

Expert Reports Can Be Expensive And May Require A Lot of Work

Expert witnesses often do not testify out of their interest in vindicating the truth. They are paid for the time they dedicate to a dispute. And in commercial disputes, they are often paid several hundred dollars an hour, or more. Some people are even professional expert witnesses, whose main job is providing expert testimony for court disputes.

A professional expert may seem less credible to a judge or jury; after all, their career depends upon providing favorable testimony to whoever pays them. But a professional expert may also be more knowledgeable about how to testify at depositions or at trial, or better able to prepare an expert report. And a professional expert may also be able to provide a list of previous cases in which other judges agreed that her testimony was persuasive, which may convince the next judge that she is reliable.

But even with seasoned experts, lawyers play a large role in preparing expert reports. This is because the lawyer best understands the specific legal issues at issue in the litigation, and so she can refine the report to focus on those issues and ensure that the report addresses each of them. It is also because experts are often not the clearest writers for lay audiences. Since the audience for the report will ultimately be non-expert lawyers, including the judge, a non-expert lawyer is well-suited to make sure someone like them will be able to understand the report. This usually involves removing unnecessary background or tangential information and replacing scientific jargon with simpler explanations.

But, of course, the lawyer cannot make edits on her own. She works with the expert to ensure that the report is accurate and the expert ultimately signs the report to confirm that its contents are accurate.

Rebuttal Reports

After each side produces an expert report, the experts review their counterpart’s reports and identify reasons why they are right and the other side is wrong. They then prepare a rebuttal report, explaining those issues. They do this to allow each side to know how the expert will criticize the other report and prepare responses to those criticisms. They also use the rebuttal report as a last opportunity to supplement the subjects about which the expert can testify at deposition at trial.

Like with the primary report, lawyers often work with the expert to prepare the rebuttal report. They do this to make sure that each subject raised in the primary report is addressed and to make sure that it can be understood by a lay audience. But since it only addresses problems in another report, it is often shorter than the primary report.