Daubert Attack On Opposing Medical Causation Experts


To prevail in a personal injury case, an essential element the Plaintiff must prove is causation. That is, the Plaintiff must prove the subject accident or incident actually caused the Plaintiff’s injury and damages. Plaintiffs typically seek to establish this element through the testimony of one or more post-accident treating physicians. However, with rare exception, the treating physician will render an opinion as to causation while lacking knowledge of vital and necessary facts, including the details of the accident, and the Plaintiff’s relevant medical, surgical, or accident history.

The reason is simple. Physicians treating litigants tend to act as doctors typically do in non-litigation treating scenarios. In a non-litigation context, doctors frequently do not need to know the exact cause of a presenting medical issue. They evaluate the symptoms and treat the condition. Generally, in the absence of a compelling reason not to, they accept the Plaintiff’s statement that the medical issue he or she now has was not a problem before the accident, but has only arisen since the accident or incident. If it is plausible the accident or incident could cause an injury of the general type the Plaintiff appears to have, the doctor will most likely conclude the accident caused the injury.

This progression, while acceptable for purposes of medical treatment, is not a reliable process for determining the cause of a medical injury or condition. The process is commonly known as the logical fallacy of post hoc ergo propter hoc (“after this, therefore because of this.”) It is a fallacy because it is based upon no other fact but sequential timing, and is therefore highly unreliable.

Prevailing Law on Medical Causation Opinion Testimony

In the case of Daubert v. Dow Pharmaceuticals, and its progeny, which is the law in all Federal Courts and the majority of states, Courts have made it clear that an expert cannot reach a reliable opinion through this process alone. Rather, medical causation experts must perform a “differential diagnosis” to render a reliable opinion. Bland v. Verizon Wireless, L.L.C., 538 F.3d 893 (8th Cir. Iowa 2008). Bowers v. Norfolk S. Corp., 537 F. Supp. 2d 1343 (M.D. Ga. 2007).

To properly perform a differential diagnosis, a physician must “rule in” all potential causes (to establish general causation), and then, one by one, “rule out” each potential cause to arrive at the most likely cause (to establish specific causation). Feit v. Great W. Life & Annuity Ins. Co., 271 Fed. Appx. 246 (3d Cir. N.J. 2008); Hendrix v. Evenflo Co., 609 F.3d 1183 (11th Cir. Fla. 2010); Cooper v. Marten Transp., LTD., 539 Fed. Appx. 963 (11th Cir. Ga. 2013); Wilson v. TASER Int’l, Inc., 303 Fed. Appx. 708 (11th Cir. Ga. 2008).

Therefore, a doctor must first learn and analyze a Plaintiff’s relevant medical, surgical, and accident history. McNabney v. Lab. Corp. of Am., 153 Fed. Appx. 293 (5th Cir. Tex. 2005); Viterbo v. Dow Chem. Co., 826 F.2d 420, 423 (5th Cir. 1987) (rejecting expert testimony where “the history used lacked reliability because it was incomplete in a critical area”, namely an awareness of the plaintiff’s relevant medical history.)

In Practice, Physicians Focus on Treating the Condition

In the course of typical treatment, physicians focus on treating the condition as it presents, and rarely take the time and effort to complete the steps required by Daubert to conduct a differential diagnosis. Also, because treating physicians are not primarily litigation consultants or witnesses, it is less likely that Plaintiff’s attorneys will have the opportunity to fully educate treating physicians on the requirements of Daubert to ensure their opinions meet the standard. Therefore, these types of opinions are particularly vulnerable to Daubert attacks.

The Plan

The attack plan starts with a thorough review of the testifying doctor’s file to ascertain (as much as possible) what the doctor did and did not do, and identify the analytic gaps.

The next step is taking the testifying doctor’s deposition. Asking some simple questions will lay the groundwork for a well-organized Daubert motion.

First, ask the testifying doctor to identify and explain the method he or she used to reach the causation opinion. Often the doctor will describe a brief interview and/or examination, the application of the “SOAP” (subjective, objective, assessment, and plan) method. A recent District Court case in Florida established this process is not adequate to satisfy the requirements of Daubert as to causation, so testimony of this nature certainly would strengthen a Daubert motion. See Carmody v. State Farm Mut. Auto. Ins. Co., 2015 U.S. Dist. LEXIS 125056 (M.D. Fla. Sept. 18, 2015).

Second, ask the testifying doctor to identify the efforts he or she made to learn the Plaintiff’s past pertinent medical history. Did he or she review medical records or images? If so, what records or images were reviewed, and from what time frame? Did he or she rely solely on the verbal representations of the Plaintiff?

Third, ask the testifying doctor to explain his or her knowledge of the Plaintiff’s accident history, and identify how he or she learned these facts. Did the doctor learn whether the Plaintiff had been involved in prior accidents, and if so, learn the facts of those accidents?

Fourth, ask whether the expert considered other potential causes. Have the doctor explain the steps he or she used to compile the list of other potential causes, and why the doctor ruled out each potential cause. This particular line of questioning is crucial in cases where a Plaintiff has obvious relevant pre-existing conditions or past injuries. If the doctor cannot provide adequate explanation as to why he or she ruled out plausible alternate causes, the Daubert motion to exclude the causation opinion will be on very solid legal ground.

Finally, ask whether the testifying doctor believes he or she has enough information to render a causation opinion. Ask whether additional information would be necessary or helpful to render an opinion within a reasonable degree of medical certainty. At this point, a testifying doctor who sees the shortcomings of a causation opinion may well take this “escape hatch.” Obviously, if the testifying doctor believes he or she lacks the necessary information to render a confident opinion, the Court may also be persuaded that this is the case, and grant a Daubert motion.

Practical Considerations

These types of Daubert motions tend to be most useful in the following scenarios:

1. Where the liability case is precarious and the damages are subjective, making them vulnerable to scrutiny;
2. Where the testifying doctor exclusively treated Plaintiff after the accident, and it is clear from the treatment notes that the doctor did not analyze pre-accident facts or data;
3. Where the Plaintiff’s claimed injury is chronic or degenerative, as opposed to acute, making cause a murkier question;
4. Where the Plaintiff has a history of prior accidents, injuries, or pre-existing conditions that plausibly cast doubt on the accident as the true (or primary) cause of the medical condition;
5. Where the case is nearing mediation, and additional leverage (such as the threat of a successful Daubert challenge or the possibility of a valid appeal) is most likely to be helpful to resolution;
6. Where the case is pending in Federal Court, with a Judge who has experience applying the Daubert standard;
7. Where the case is pending in a state where Daubert has been recently adopted, and experts and Plaintiff’s lawyers have less experience navigating the more exacting requirements for reliable opinion testimony (Florida, for example).


Carefully setting up and preparing a well-founded Daubert motion can apply valuable pressure at a critical point in your case. A full Daubert hearing can be a time-consuming and expensive process that many Plaintiffs’ attorneys simply wish to avoid. If the goal is a reasonable settlement, a mediator can make significant progress explaining the potentially devastating ramifications of a successful Daubert motion to a Plaintiff.

Also, your opponent will realize the motion, if granted, may result in the exclusion of vital evidence, and potential inability to establish an element of the case. This in turn could lead to additional motions for directed verdict or summary judgment your opponent will be forced to defend. Finally, even if a valid Daubert motion is unsuccessful in trial court, but supported by the law, it may give rise to a valid appeal, casting a specter of uncertainty even in the event of a verdict for Plaintiff.

Therefore, irrespective of whether the motion is granted, filing these motions can be strategically beneficial. In the appropriate cases, Defense attorneys will be well-served by using these tactics to set up and execute strong Daubert motions to attack the opinions of medical causation experts.


 – Christopher Barkas, Shareholder

 – Elizabeth “Betsy” Burgess, Shareholder


To read the original article as published in USLAW magazine, please click here.


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