A Rule 702 order on general causation resulted in summary judgment in more than 250 cases in the In re Baby Food MDL. Here’s how it happened and why the plaintiffs didn’t get a second try.
Plaintiffs alleging that a product caused their disease or disorder must establish both that the product can cause it (general causation) and that it did so in their case (specific causation). Because mass tort plaintiffs share similar general causation questions, multidistrict litigations (MDLs) and other coordinated actions often address general causation first. Without admissible expert testimony on general causation, plaintiffs’ cases are futile, and specific causation need not be addressed.
Of course, plaintiffs rarely concede defeat. For example, if a court addresses general causation by excluding the experts disclosed by a small group of bellwether plaintiffs, other plaintiffs argue that they should be allowed to disclose their own experts rather than be tethered to the excluded bellwether experts. Some courts are receptive, but the second round of experts rarely fares better than the first (as we discussed here and here). A more efficient approach is to litigate general causation once on behalf of all plaintiffs in a mass tort litigation who must establish it. A recent order from the In re Baby Food Products Liability Litigation, 2026 WL 3077421 (N.D. Cal. Oct. 14, 2026), provides guidance on how to set up such an approach that anticipates and overcomes allegations of unfairness.
The plaintiffs in the In re Baby Food MDL alleged through their guardians ad litem that they had developed autism spectrum disorder (ASD) and ADHD from consuming certain baby food products. To “efficiently steer” the litigation, the court phased discovery, addressing general causation (whether the products can cause ASD and ADHD) before specific causation (whether they caused any particular plaintiff’s condition). Following a multiday hearing, the court held that the plaintiffs had not met their burden of establishing that their general causation experts’ opinions were admissible under Federal Rule of Evidence 702 and excluded them. The defendants then moved for summary judgment, arguing that without admissible general causation evidence, the plaintiffs could not prove an essential element of their claims.
The plaintiffs first argued the court could not enter summary judgment because there had been no discovery as to the actual exposure levels of any individual plaintiff. The court rejected that argument, citing plaintiffs’ counsel’s comments at a June 2024 case management conference about the bifurcated discovery plan and the scope of the first phase. As the court noted, “since June 2024, the general causation question has been clear.” Moreover, the plaintiffs conceded that the exclusion of the proposed general causation experts would apply in the individual plaintiffs’ cases. Without admissible general causation evidence, the plaintiffs’ specific causation arguments “unravel[ed].” As the court put it, “[t]hat is the end of it.”
The plaintiffs next tried to limit the exclusion’s reach. They argued that it would violate due process to apply the exclusionary order to any plaintiff who filed directly in the MDL after the excluded experts’ reports were served in May 2025, reasoning that those plaintiffs did not participate in the exchange of those reports. But, as the court recounted, the court had indicated at a March 2025 case management conference that “because we’re doing general causation we have to have a deadline for plaintiffs to join so that they’re bound one way or the other.” At a subsequent conference, the court set November 21, 2025 as the deadline for plaintiffs to file directly into the MDL. Thus, beyond being represented by Plaintiffs’ Steering Committee counsel and voluntarily filing directly into the MDL, the plaintiffs in question “had ample opportunity to provide input, or otherwise petition the [c]ourt for additional relief” prior to the December 2025 hearing on the defendants’ Rule 702 motions and the February 2026 order excluding the plaintiffs’ general causation experts. Citing the broad discretion MDL courts have “to structure a procedural framework” and implement “workable programmatic procedures,” the court stood by its cutoff date and held that the plaintiffs’ failure to request additional discovery ahead of the hearing “is not a due process violation.” The court granted the defendants’ motion for summary judgment as to more than 250 cases in the MDL that alleged ASD or ADHD.
In re Baby Food illustrates not only the efficiency of addressing general causation in a way that applies across an entire mass tort litigation but also the value in a court clearly communicating the stakes and ground rules before beginning the process. When thoughtful case management is followed by rigorous Rule 702 gatekeeping and insistence on staying the course that the court has charted, a single order can resolve hundreds of cases at once.
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