It happens frequently between opposing medical experts in litigation. One side brings on a consulting medical expert to look for holes in the work of the testifying medical experts on the other side. But what happens when one medical expert exposes another medical expert's work as flawed – and both medical experts are working for you? What if your own expert comes to you and questions the methods or conclusions of another of your experts?
Perhaps you retained one expert as a consultant to conduct initial reviews and lay the groundwork for your case. Later, you retained a second expert in the same field to testify. You present the consulting expert's work to the testifying expert as background to be used in formulating his own opinion. The testifying expert looks at the earlier work and proclaims, "I don't agree with this. The analysis is flawed for such and such a reason."
At this point, there is no option of sweeping the issue under the rug. Had the consulting expert's work remained just that, it would not have been discoverable under the federal rules. But once it was provided to the testifying expert, it became fair game. That means that your opponent is likely both to learn about the consulting expert's work and also to learn of the testifying expert's condemnation of it.
One way to deal with this is to use this as an opportunity to build the testifying expert's credibility. Establish that the testifying expert is so independent that he even criticized your consulting expert. And be sure to have the testifying expert explain what errors the consulting made and why his expert opinions are more reliable.
That said, the better route is to avoid getting into the situation in the first place. The only way to do that is to not disclose the consulting expert's opinions to the testifying expert. If the work done by the consulting expert is reviewed by the testifying expert, and particularly if it becomes part of the testifying expert's file, then it is discoverable, and your testifying expert will be questioned about it in deposition. So, as a rule, it would be prudent to avoid allowing one expert to see the other's work.
While the main reason not to reveal a consulting expert's work to a testifying expert is to protect the earlier work from discovery, there is also another reason. If the second expert testifies based on the work of the first expert, then the testimony is based on hearsay. The federal rules of evidence allow this but it creates a dilemma. The expert's reliance upon that hearsay does not establish the foundational fact established by the hearsay and the expert still has to prove that foundational fact, which is probably going to require the attorney to put the consulting expert on the stand. This defeats the purpose of having a consulting expert in the first place. And of course, no attorney wants their testifying expert to rely on hearsay from their consulting non-testifying expert.
