We write on the heels of a long weekend layered with dogs and fun.  The National Dog Show, which you may have watched on TV yesterday, is held about ten minutes from our house, and a fabulous corded Standard Poodle named Joel, who just happens to be “family” (he is the sire of our gorgeous puppy, Luca) won Best of Opposite Sex two days running (and stayed overnight with us).  And two out-of-town handlers we know unexpectedly needed a place to exercise their charges, so we twice got to stand in our back yard while no fewer than seven show dogs, from ten pounds to 150 pounds, swirled around us.  We can’t imagine being much happier.

Layers of good mark today’s case, as well.  Arevalo v. Mentor Worldwide LLC, et al., 2022 WL 16753646 (11th Cir. Nov. 8, 2022), is a decision on the appeal of a Northern District of Florida decision we liked very much.  Arevalo is a pelvic mesh case.  The plaintiff alleged that mesh devices implanted to treat her stress urinary incontinence and pelvic organ prolapse caused her to undergo mesh removal surgery and to suffer a familiar litany of injuries.  The plaintiff’s general and specific causation expert was the ubiquitous Dr. Bruce Rosenzweig.  Among numerous other motions, the defendant moved to exclude Dr. Rosenzweig’s specific causation opinion as unreliable because Dr. Rosenzweig did not perform an adequate differential diagnosis.  The court granted the motion and excluded the specific causation opinions, holding that Dr. Rosenzweig “did not explain how he systematically and scientifically ruled out the other potential causes for the plaintiff’s symptoms.  Arevalo, 2022 WL 1673646 at *4.  The court then granted summary judgment for the defendant because the plaintiff could not reach the jury without expert specific causation testimony.  The plaintiff appealed to the Eleventh Circuit, and today’s decision is the result. 

As the Eleventh Circuit explained, the “differential diagnosis methodology is a medical process of elimination where by the possible causes of a condition are considered and ruled out one –by-one, leaving only one cause remaining.”  Id. at *4 (internal punctuation and citation omitted).  “To be reliable,” the court continued, “a differential analysis need not rule out all possible alternative causes but must at least consider other factors that could have been the sole cause of the plaintiff’s injury.”  Id. (internal punctuation and citations omitted).  The court emphasized, “If properly followed, a differential diagnosis can be a reliable methodology under Daubert. . . . But an expert does not establish the reliability of his techniques or the validity of his conclusions simply by claiming that he performed a differential diagnosis on a patient.”  Id. (internal punctuation and citations omitted).  And that, the court held, was exactly what Dr. Rosenzweig did:  in his expert report, the doctor listed a number of potential non-mesh causes for the plaintiff’s injuries, then stated, without elaboration, “None of these conditions led to the current injuries she is suffering from.”  Id. (sentence-ending preposition in original).  And while the plaintiff stated, in her opposition to the defendant’s summary judgment motion, that Dr. Rosenzweig had properly ruled out alternative causes of her symptoms, she “did not attach or even refer to any part of Dr. Rosenzweig’s deposition testimony,” instead relying exclusively on the conclusory statements in the expert report.  Id.  

Affirming the district court, the Eleventh Circuit held:

The district court did not abuse its discretion when it excluded Dr. Rosenzweig’s specific causation opinions.  In his cursory report, Dr. Rosenzweig offered no explanation – let alone any scientific support – for ruling out the potential alternative causes that he had identified. . . . A reliable differential diagnosis requires the expert to offer some explanation for how he ruled out an alternative cause.

Id. at *5 (emphasis in original).

The court concluded, [I]t is not [the plaintiff’s] post hoc explanations that matter to the reliability analysis.  The district court’s criticism of Dr. Rosenzweig for omitting an explanation for ruling out those . . . potential causes is valid.”  Id.

The court also held that the district court had not erred in denying reconsideration of its order.  When she moved for reconsideration, the plaintiff finally provided the court with the full transcript of Dr. Rosenzweig’s deposition, but the district court held that this was not “newly discovered evidence” – the deposition testimony was available when the original motion was filed – and that a party could not use reconsideration “to relitigate old matters, raise argument or present evidence that could have been raised prior to the entry of judgment.”  Id. at *6.

Next, the court affirmed the district court’s decision to strike the plaintiff’s “Hail Mary” disclosure of a new expert more than three years after the expert disclosure deadline and less than three weeks after the district court excluded Dr. Rosenzweig’s opinions.  The court held that the record supported the district court’s conclusion that the plaintiff did not have a good reason for the late disclosure and that the disclosure prejudiced the defendant.  (The new expert was not disclosed until after discovery had closed, depriving the defendant of an opportunity to depose the doctor or submit a rebuttal report.)

Finally, the court affirmed the grant of summary judgment for the defendant, rejecting the plaintiff’s argument that her treating physician’s deposition testimony – which, the court held, was “speculative and equivocal” – was enough to “create a factual dispute about specific causation sufficient to withstand summary judgment.”  Id. at *8. 

We like Arevalo for so many reasons, perhaps most of all because this expert, along with so many others, has skated past exclusion far too many times despite “differential diagnoses” (more properly, differential etiologies) that include none of the analysis necessary to properly rule out alternative causes.  “Differential diagnosis” provides an easy “out” for a passive judge, and we are pleased that neither the district court judge nor the Eleventh Circuit panel fell into that trap.  

We hope that your Thanksgiving was peaceful.  We will talk to you soon.