We are headed to New York on Monday for the A.C.I. Drug and Medical Device Conference.  We love this conference – we always see so many old friends and former colleagues – and we are delighted that it is back “in person” this year.  We are speaking on a panel about the proposed amendments to Fed. R. Evid. 702, and today’s decision – a terrific opinion excluding an expert in a hernia mesh case – fits right into the “good results that set the bar” column of our outline.

In Northrup v. Covidien, L.P., 2021 U.S. Dist. LEXIS 227025 (C.D. Cal. Nov. 24, 2021), the plaintiff, who had a history of multiple abdominal surgeries and hernia repairs, underwent hernia repair with the defendant’s hernia mesh in September 2013.  At the time, he had “extensive adhesions’ of his bowel to his abdominal wall as a result of his previous surgeries.  In March 2016, he presented with abdominal pain and gastrointestinal symptoms.  One doctor recommended that he stop taking testosterone and steroids.  Another, several months later, theorized that the symptoms might be related to long-term use of narcotic painkillers.  Later that year, the surgeon who had performed the mesh implant treated the plaintiff with nerve block injections, which provided only temporary pain relief.

In January 2018, the implanter performed surgery to removed tacks and sutures he had had used in the 2013 implant surgery.  Two months later, he operated again, this time to remove the mesh and all remaining tacks and sutures.   The surgical note indicated that the plaintiff had “dense, fibrotic, chronically inflamed and scarred down adhesions.”  Northrup, 2021 U.S. Dist. Lexis 227025 at *3.  The surgeon testified that he removed all of the mesh and did not observe problems with the mesh itself.

The plaintiff’s abdominal pain persisted.  He “sought medical care seven times in 2019,” id. at *4, and he filed suit in 2020, asserting claims sounding in strict liability and negligence for failure to warn, design defect, and manufacturing defect.  The defendant moved to exclude the opinions of the plaintiff’s expert and moved for summary judgment on all of the plaintiff’s claims.  We knew we were going to like the resulting opinion when the court setting forth the legal standard applicable to the summary judgment motion, emphasized that it was “not the court’s task to scour the record in search of a genuine issue of triable fact” – that it “need not examine the entire file for evidence establishing a genuine issue of fact where the evidence is not set forth in the opposition papers with adequate references so that it could conveniently be found.”  Id. at *7 (internal punctuation and citations omitted).

Unsurprisingly, the plaintiff’s expert offered the opinion that all of the plaintiff’s symptoms were caused by the defendant’s mesh.  The defendant argued that the opinion was inadmissible because it was not the product of any scientific methodology.  And the court agreed – resoundingly.  The court explained that, while the expert did not identify any methodology in his expert report, he testified in his deposition that the performed a “differential diagnosis.”  Emphasizing that “differential diagnosis has long been recognized in [the Ninth Circuit] as a reliable methodology, so long as it is properly conducted,” id. at *8 (internal punctuation and citations omitted), the court set forth the elements of a reliable differential diagnosis under Ninth Circuit law:

First, an expert should compile a comprehensive list of hypotheses that might explain the set of salient clinical findings.   Failure to consider even a rare explanatory hypothesis may be indicative of unreliability.  Next, the expert must eliminate hypotheses until a conclusion is reached as to the most likely cause of the findings at issue.  The expert must provide reasons for rejecting alternative hypotheses using scientific methods and procedures, and the elimination of those hypotheses must be founded on more than subjective beliefs or unsupported speculation.

Id., at *8-9 (internal punctuation and citation omitted.)  In other words, to perform a reliable differential diagnosis (or, more accurately, differential etiology), the expert must “rule in” all possible causes of the alleged injuries, then “rule out” causes scientifically until he or she arrives at his causation opinion.

But the plaintiff’s expert (like so many others claiming to employ this methodology) did none of this.  Asked, in his deposition, to lay out his thought process “step by step,” he testified, “I used a thought process – for example, issues related to pain or any other factors and then arrived at a conclusion . . . .”  Id. at *9.   Asked to describe this “thought process,” he replied, “It’s called a brain.”  Id.  (Note to self:  find a way to take this guy’s deposition someday, preferably after a really bad week.)  Asked whether he made a list of possible causes of the plaintiff’s symptoms, he stated that he “ruled in all the potential causes that he felt were appropriate,” but that such a list “would be endless.”  Id. at *9-10.  Asked how he eliminated alternative causes, he answered, “This isn’t an elimination game.”  Id. at *10.  Finally, asked whether he ruled out the plaintiff’s prior surgeries as the cause of his symptoms, he answered, “I did not rule out anything.”  He concluded, “I cannot give you any specific details in regards to how I came to [my conclusions] or what the conclusions entailed in terms of the factors.”  Id.   

By now, we are certain that the phrase “ipse dixit” has occurred to all of you.  And the court agreed.  The court held,

[The expert’s] testimony is not sufficient to establish by a preponderance of the evidence that he conducted a proper differential diagnosis.  Even assuming that [he], notwithstanding his failure to compile a ‘comprehensive list,’ did consider all possible causes of Plaintiff’s abdominal pain, there is no evidence of any reasoned basis for the elimination of any potential cause other than the . . . mesh.  Indeed, it is difficult to discern how [he] arrived at his conclusion, given his testimony that he did not rule out any other potential causes and his inability to provide ‘any specific details in regards to how [he] came to those conclusions.’

Id. at *11.   The court concluded, “Absent any indication that [the expert]’s causation opinion was the product of a properly conducted differential diagnosis, or any reliable methodology, his opinion is not admissible.”  Id.

We like so much about this.  We love the fact that the court applied the correct “preponderance” standard to its admissibility analysis.  (One of the proposed amendments of Rule 702 adds “preponderance” language to the Rule, emphasizing the burden a proponent of expert testimony must satisfy to surmount the threshold admissibility standard.)   And we love the emphatic smackdown of the sort of nonsense we see on a daily basis.

The court went on to exclude the expert’s design defect opinion because he was not qualified to offer the opinion.  (Once again, the expert ably helped dig his own grave, testifying that he couldn’t remember if any of the mesh he’d removed during his career was the type of mesh the defendant manufactured.)   Finally, the court excluded the expert’s opinion that the defendant’s Instructions for Use (IFU) were inadequate.   In an earlier case, the expert had testified that he could not comment on the warnings that should be included in an IFU, as that was “the manufacturer’s responsibility.”  In this case, he testified that he had not looked at any IFU in fifteen to twenty years.

Once the court excluded the expert’s opinions, the rest was easy: summary judgment for the defendant on all claims because the plaintiff had no admissible evidence to support them.  An all-around satisfying opinion that “gets it right” on all counts.  We hope to see many of you at ACI this week – please say hi to us if you are there!  (Bexis will be there too, speaking on a different topic.)  In the meantime, stay safe out there.