Science and law share a common goal—getting at the truth; but their relationship can be shaky. In areas like medicine and products liability, courts need to rely on science, but courts should not make science or get ahead of science. Science is a methodical process that relies on testing, peer review, and replication. When science remains unproven, it needs to remain out of the legal system. Prematurely adopting scientific findings into legal standards—before they have been thoroughly validated—can lead to institutionalizing unverified science and the creation of legal precedents that are difficult to overturn. Science has to lead and the law has to follow. We have written about the consequences of the reverse. Today, we talk about a case that put things in the right order.
Plaintiff in Davey v. Safeway Inc., 2025 Cal. Super. LEXIS 5572 (May 5, 2025), ingested over-the-counter acetaminophen while pregnant with her son. Her son was later diagnosed with autism spectrum disorder (ASD) which plaintiff blames on the prenatal exposure to acetaminophen. The drug’s label included an FDA-required warning that: “if pregnant or breast-feeding, ask a health professional before use.” Plaintiff brought warning, negligence, and implied warranty claims alleging that defendants should have included a warning that “prenatal ingestion of acetaminophen may cause ASD.” Id. at *1-2. But there was no science to support that warning at the time of plaintiff’s ingestion, and there remains none today.
The court summarized the issue:
This case raises the question of when a duty to warn of a specific health concern arises – above and beyond a general warning to discuss the matter with a medical professional — where the underlying science relating to the concern was (and remains) highly uncertain despite ongoing and extensive review by government regulators and independent medical entities alike.
Id. at *1. The answer is there is no such duty.
The case thoroughly sets out the “state of the science,” which not surprisingly was described differently by the parties. But rather than try to resolve those differences, the court looked to “a series of literature reviews conducted by federal regulators and independent medical entities.” Id. at *10. The upshot of which was that the available scientific evidence regarding the potential relationship between acetaminophen and ASD was “too limited to make any recommendations and did not warrant any changes to the FDA’s [required warning].” Id. at *11. As recently as 2023, the FDA’s continued review of the evolving science found that the “outcomes remain mixed” and do not alter its prior conclusions. Id. at *17-18.
Under California law, a drug manufacturer is required to warn about “known or reasonably scientifically knowable dangerous propensities of its product.” Id. at *24. The concept of what is a knowable risk is inherently tied to the state of the science:
Consequently, “[t]he strength of the causal link . . . is relevant both to the issue of whether a warning should be given at all, and, if one is required, what form it should take.”
Id. at *26 (quoting Finn v. G.D. Searle & Co., 35 Cal.3d 691, 701 (Ca. Sup. Ct. 1984).
Both the FDA and courts recognize that over-warning poses its own risks. It can lead to dilution of important warnings, consumer disregard, or could dissuade a consumer from using a needed product.
Based on the state of the science, which was “profoundly uncertain and conflicting,” the court concluded as a matter of law that the “existence of any causal link [between acetaminophen and ASD] was neither known or scientifically knowable.” Id. at *28.
The court was not persuaded that internal company analyses that included some “expressions of concern,” changed the legal conclusion:
That a company that makes pharmaceuticals regularly reviews the literature potentially relevant to the safety of its products and supports candid internal discussion, however, is positive corporate behavior. While these discussions show awareness of the science, they do not change the state of that science.
Id. at *28-29. And the state of the science warranted summary judgment.
We will acknowledge that there is another ruling in this opinion—rejecting defendants’ preemption defense. But we are not going to talk about that because the case reached the right conclusion anyway. And, with the court’s heavy reliance on the FDA’s review of the literature, the state of the science functions essentially the same as a preemption ruling that no “newly acquired information” existed to support a label change.