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We posted just the other day about widespread judicial reluctance to follow the expert admissibility standards imposed by Federal Rule of Evidence 702.  We called out the Eighth Circuit as a prime example of that problem, and we discussed the committee-approved amendments to Rule 702 that are intended to reinforce the need for expert opinions to have sufficient evidentiary bases.  As the Advisory Committee has stated, “[M]any courts have held that the critical questions of the sufficiency of an expert’s basis, and the application of the expert’s methodology, are questions of weight and not admissibility.  These rulings are an incorrect application of Rules 702.”  See Proposed Committee Note (emphasis added).

Little did we know that the Eighth Circuit would strike again on the very day that we published that post.  In In re Bair Hugger Forced Air Warming Devices Products Liability Litigation, No. 19-2899, 2021 WL 3612753 (8th Cir. Aug. 16, 2021), the Eighth Circuit reversed one of the most rigorous and faithful applications of Rule 702 that we have seen.  You can read our take on the district court’s order here.  In short, the plaintiffs put forth two general theories on how the defendants’ patient warming devices purportedly caused joint infections during surgery—the “airflow disruption theory,” under which heat from the devices created air currents that carried bacteria to the surgical site; and the “dirty machine” theory, under which the devices were internally contaminated and blew bacteria into the operating room.  Id. at *2.  The district court ruled that the plaintiffs’ experts’ opinions on these general causation theories did not meet Rule 702, mainly because they included large analytical gaps and were not generally accepted.  Id. at *3.

The Eighth Circuit decided that it knows better, and in using that phrase, we are not being glib.  The Eighth Circuit literally reanalyzed the issues and substituted its own discretion for the district court’s.  That is too bad, because the district court’s order was exceptionally well informed.  The publication on which plaintiffs most heavily relied itself found no “causal basis” and admitted to confounding factors.  Id. at *6.  In addition, no studies had shown an increase in surgical site infections related to the warming devices; the FDA was “unable to identify a consistently reported association”; and an international meeting on the topic found a “strong consensus that there was ‘no evidence to definitively link’ forced-air warming to an increased risk of [joint infections].”  Id. at *14.  The district court also had the benefit of full-blown cross-examination at trial of the plaintiffs’ experts before it ruled that the opinions were not admissible.  An order finding causation opinions unreliable under these circumstances would be difficult to overturn.

But the Eighth Circuit found a way, and its opinion simply cannot be squared with Rule 702.  There are two reasons.  First, the opinion is replete with statements commending the “liberal thrust” of Rule 702, and the panel hangs its hat firmly on the “flexibility” of the reliability inquiry and the “general rule [that] the factual basis of an expert opinion goes to the credibility of the testimony, not the admissibility.”  E.g., id. *4-*5.  We understand that the Eighth Circuit has long been a bit Jekyll and Hyde on Rule 702, with proponents of expert opinions generally citing Bonner v. ISP Technologies and objectors citing Glastetter v. Novartis—Eighth Circuit cases decided the same year, but going in opposite directions.

Any debate, however, on whether the factual basis for an expert’s opinion goes to admissibility should be settled.  It does.  The Advisory Committee certainly thinks so:  “[Rule 702] does not mean, as certain courts have held, that arguments about the sufficiency of an expert’s basis always go to weight and not admissibility.”  Proposed Committee Note.  We explained it further in our prior post, but suffice it to say here that the district court was fully justified in examining the basis for the experts’ opinions in ruling on admissibility.  It was acted as the gatekeeper, as it should have.

Second, although the Eighth Circuit mouthed the words “abuse of discretion,” it most assuredly did not apply that standard.  Instead the panel reanalyzed the issues and parsed the record, and it concluded that it did not matter so much that the plaintiffs’ key publication found no “causal basis,” even though the issue was causation.  The court ruled that gaps identified by the district court really were not so wide and that limitations in the medical literature really were not so profound.  As noted above, this was the Eighth Circuit substituting its discretion for the district court’s.

Perhaps most notably, the Eighth Circuit faulted the district court for excluding the opinions partly for lack of general acceptance because the issues were currently the focus of “scientific research and debate.”  Id. at *14.  This is backward.  Stating that causation is still being debated does not change the fact that causation has not been established.  The district judge understood this point and quoted a line from Rosen v. Ciba Geigy that we have used more times than we can count:  “[T]he courtroom is not the place for scientific guesswork, even of the inspired sort.  Law lags science; it does not lead it.”

The upshot is that the Eighth Circuit faulted the district court for fulfilling the gatekeeper role that Rule 702 commands.  That is unfortunate, and we hope that district judges will take guidance from other Eighth Circuit opinions that call for more discipline.  (Have we mentioned Glastetter.)  When we wrote about the district court’s order, we predicted that the Eighth Circuit would affirm.  Well, from time to time we get those wrong, but we can make one prediction for sure:  In re Bair Hugger will be in our Bottom Ten Cases for 2021.