Yesterday we did our annual best of/worst of CLE, “The Good, the Bad and the Ugly: The Best and Worst Drug/Medical Device and Vaccine Decisions of 2025”. It was good fun for us presenters and hopefully at least mildly educational and entertaining for the audience. (If you missed it, the video replay will be available later today at this link, and you can get CLE credit to boot).
One thing that was striking about this year’s countdown was how many opinions involved expert exclusion and Federal Rule of Evidence 702—7 out of 20 cases. Expert exclusion issues are a key part of our practice, of course, but these cases made their respective lists because they either recognized that the 2023 amendments to Rule 702 intended to halt overly permissive, let-it-all-in-and-let-the-jury-sort-it-out approaches to expert testimony, or they flagrantly got it wrong.
Today’s post is about another Rule 702 opinion, and in particular its Georgia state court analogue, OCGA § 24-7-702 (b). Sterigenics U. S., LLC v. Mutz, 923 S.E.2d 176 (Ga. Ct. App. 2025) is a little bit older (October 31, 2025) and involves expert testimony on general causation in a so-called “toxic tort” case involving ethylene oxide (EtO) emissions from a sterilization facility. But it has application to our pharmaceutical and medical device area, so it is worth a closer look.
The appeals in Sterigenics arose from eight bellwether cases in which plaintiffs alleged that exposure to EtO caused various cancers and birth defects. The trial court had granted in part and denied in part motions to exclude expert testimony and for summary judgment, prompting cross-appeals from both sides.
As you would expect, in addition to establishing exposure to the alleged agent that cause harm, plaintiffs in Georgia must offer proof of general causation — that exposure to a substance is capable of causing a particular injury or disease — and proof of specific causation — that exposure to a substance under the circumstances of the case contributed to his illness or disease.
The core question before the Court was whether Georgia courts should adopt the Eleventh Circuit’s framework for evaluating the reliability of expert testimony on general causation under Georgia Rule 702(b), which is materially identical to Federal Rule of Evidence 702.
The Court held, as a matter of first impression, that Georgia courts should indeed apply the Eleventh Circuit’s approach to Rule 702 and its approach to general causation in toxic tort cases derived from McClain v. Metabolife Intl., Inc., 401 F.3d 1233 (11th Cir. 2005).
On Rule 702, Sterigenics said all the right things: Trial courts must act as gatekeepers and assess the reliability of proposed expert testimony; they must consider whether the expert’s methodology is sufficiently reliable; and the proponent of the expert testimony bears the burden of establishing that reliability or the testimony will not be admitted.
With the Rule 702 parameters established, Georgia agreed with McClain’s approach of dividingtoxic tort cases into two categories:
- Category One: Cases in which the medical community routinely and widely recognizes that the chemical at issue is both toxic and causes the type of harm alleged (e.g., asbestos causing mesothelioma). In such cases, courts need not undertake an extensive analysis of expert testimony regarding general causation (whether that agent is capable of causing the harm alleged to humans, at the exposure level established) and the focus shifts to specific causation (did the agent cause the harm in this instance.
- Category Two: Cases where the medical community does not generally recognize the agent as both toxic and causing the alleged injury. Here, plaintiffs must establish general causation through reliable expert testimony, with courts paying careful attention to the expert’s dose-response analysis and whether a harmful level of exposure has been identified.
The trial court had adopted a “third way,” treating EtO as falling between the two categories and admitting expert testimony that “any exposure” to EtO could cause harm without requiring a specific dose-response relationship. The Georgia Court of Appeals rejected this, clarified that, while precise quantitative dose-response evidence is not required, experts must lay a reliable groundwork for determining the dose-response relationship or otherwise establish causation through accepted scientific methodologies.
On remand, the trial court must first determine whether EtO is routinely and widely recognized by the medical community as both toxic and causative of the alleged harms. If so, the focus shifts to specific causation (and the reliability of expert testimony regarding same). If not, the court must rigorously assess the reliability of the plaintiffs’ general causation experts, including their dose-response analysis and consideration of alternative methodologies.
We applaud Georgia to the extent is has better aligned state practice with federal standards and reinforced the importance of rigorous judicial scrutiny of expert causation testimony.