This post is from the non-Butler Snow side of the blog.

When you represent medical device manufacturers in product liability litigation, you will deal with allegations that a device broke or failed because of what it was made from, and you will encounter both experts and “experts” (scare quotes intended) in materials science. 

Materials science is the interdisciplinary study and analysis of product composition with application to the design, development and manufacturing of real products.  It is something we have found weirdly interesting, ever since an amazing materials scientist explained that a favorite blazer with a nubbly texture never wrinkled because it had “predetermined collapse points.”  Because of those predetermined collapse points, the garment never took on additional collapse points (aka wrinkles), no matter how badly it was squished in a suitcase. 3D printing/additive manufacturing is another area of interest to the blog, and another area where materials science matters quite significantly. 

With that short detour over , turn with us now to Hill v. Medical Device Bus. Srvcs., Inc., No. 3:21-cv-0440, 2024 U.S. Dist. LEXIS 140272, 2024 WL 3696481 (M.D. Tenn Aug. 7, 2024), a case in which the plaintiff’s materials science expert was challenged and excluded, for good reason.

The plaintiff in Hill had two hip replacement surgeries.  A 2014 surgery was for the initial implant of his total hip replacement system, and a 2015 surgery was to replace certain components, although one component, the femoral stem, was left unchanged.  Five years later, the femoral stem component fractured, and the entire hip implant construct was explanted and replaced. 

According to the court, the parties seemingly agreed that the femoral stem component broke due to a small flaw in its metal, “but they disagree[d] as to how that flaw came to exist”:

Defendant’s experts assert that a flaw was introduced to the product during surgery from the use of electrocautery… [whereas] Plaintiffs assert that a flaw was introduced to the product during the manufacturing process.

Hill, 2024 U.S. Dist. LEXIS 140272 at *4.

As our readers know, expert testimony is measured against the standard in the updated Federal Rule of Evidence 702, which emphasizes the importance of the gatekeeping function of our courts:

A witness who is qualified as an expert by knowledge, skill, experience, training, or education may testify in the form of an opinion or otherwise if the proponent demonstrates to the court that it is more likely than not that:

(a) the expert’s scientific, technical, or other specialized knowledge will help the trier of fact to understand the evidence or to determine a fact in issue;

(b) the testimony is based on sufficient facts or data;

(c) the testimony is the product of reliable principles and methods; and

(d) the expert’s opinion reflects a reliable application of the principles and methods to the facts of the case.

To its credit, the Hill court recognized the changes to Rule 702 were meant to give it more teeth, and that courts “can exclude a conclusion if it is based on methods that are unreliable (and thus do not serve to reliably substantiate the conclusion[)]”.

The Hill court also realized that Sixth Circuit cases applying the pre-amendment version of Rule 702 might be amongst the “misguided cases” that led to rules Advisory Committee to update Rule 702.  But—in the only really confounding part of the opinion, footnote 9—the court believed that it had to follow Sixth Circuit authorities interpreting the previous version of Rule 702 even though Rule 702 itself has changed.  See here for contrary Supreme Court precedent recognizing that rules changes, like statutory changes, overturn prior judicial precedent.

The good news is, the court did not need to resolve any finer points of the pre- versus post-Rule 702 amendment test to conclude that the plaintiffs’ materials science experts’ opinions were inadmissible.

Plaintiffs’ first expert was a well-credentialed materials scientist who opined that the critical flaw in the implant’s femoral stem was introduced during manufacturing, and that she had ruled out all other potential causes for the flaw.  But, as the court recognized, she did not actually have any evidentiary basis for ruling out those other potential causes: 

For example, she ruled out that the failure was caused by the Implant being placed at the improper angle during surgery, but [Plaintiffs fail] to explain how she can give that opinion when (as Plaintiffs do not dispute) she does not know the proper angle at which the Implant should have been placed.  If she does not know what angle is improper, then she lacks a basis for saying that an improper angle did not cause the break.  Similarly, she lacks a basis to rule out “trauma and blunt force” during surgery . . . because she did not know anything about how the surgery was conducted.

Hill, 2024 U.S. Dist. LEXIS 140272 at *21.

Moreover, although this expert testified it was possible for the flaw to have been introduced during manufacturing, the expert did not examine whether the defendant had appropriate measures in place to control the size of flaws during manufacture of its metal implants.  Thus, she couldn’t actually tie the flaw in the plaintiff’s implant to the manufacturing process or to the reason the plaintiff’s implant broke.

With the plaintiffs’ first expert out, the second expert also had to be excluded:  part of his opinion merely parroted the first expert and thus was unreliable, and the rest of his opinion was predicated on statements that the first expert never expressed.

With both of plaintiffs’ experts out, the Court concluded (quite rightly) that the burden of proof meant it did not need to consider challenges to the defendant’s experts and instead could just move on to the defendant’s motion for summary judgment.  

Without experts to establish causation, summary judgment should have been—and was—a relatively easy grant.  But plaintiffs tried one last gambit, the res ipsa loquitur-like malfunction theory:  that the factfinder can infer defectiveness merely from the existence of an alleged malfunction and a negation of other causes. 

We don’t buy the malfunction theory, just as we look askance at other variations of res ipsa loquitur.  When the malfunction theory is accepted, it is supposed to be fairly rigorous:  If the plaintiff can show that the product malfunctioned, and if the plaintiff also can negate all other causes for the malfunction other than a product defect, then the malfunction theory is applicable and an inference of a product defect is permissible.

But we find it often is trotted out just because the plaintiffs’ counsel or experts haven’t done their homework and are missing key pieces of evidence.  The device must have had a defect, they will argue, because devices don’t just fail. 

But the reality is that medical devices, particularly implanted medical devices, do fail for unknown reasons—and plaintiff’s second expert admitted as much here.  And when the plaintiff has not actually negated all other causes of malfunction, then the malfunction theory just doesn’t apply:

[W]hen a device is known to fail for unknown reasons, it is pure speculation that a failure is attributable to a manufacturing defect and not some other unknown cause without evidence supporting one cause over another.

Hill, 2024 U.S. Dist. LEXIS 140272 at *49.

The plaintiff in Hill certainly did not negate all other potential causes of malfunction, and so the court came to the right conclusion:  The defense wins.

An appeal has been filed, so we shall see if the Sixth Circuit agrees.

Our thanks to Robyn Maguire and Sarah Jin of Barnes & Thornburg for sending the case and a congratulations as well for the nice win!