After nearly three years of litigation winding through California’s appellate courts, the closely watched Gilead Tenofovir Cases is finally set for oral argument before the California Supreme Court on Wednesday, May 6, 2026, at 9:00 a.m. in San Francisco. The case presents a question with potentially sweeping consequences for product liability law: Does a pharmaceutical manufacturer owe a duty of reasonable care to users of a non-defective medicine when making decisions about the development of an allegedly safer and equally effective alternative compound? Based on long-standing and well-grounded principles of tort law, the correct answer is that no such duty exists or should exist.
Of course, our view on this controversy is well known, having covered the case here, here, here, and here. For the upcoming oral argument in the California Supreme Court, here is what you need to know.
The dispute centers on Gilead Sciences and its development of live-saving and life-extending HIV antiretroviral medicines. The plaintiffs are patients who used medicines containing tenofovir disoproxil fumarate (“TDF”) and allegedly experienced warned-of side effects. A positive HIV test was once considered a death sentence, but TDF-based medicines, which the FDA first approved in 2001, changed that and have been credited with saving countless lives.
Most importantly, the plaintiffs do not allege that the TDF medicines they used were defective in design, manufacture, or labeling. That’s right, no alleged product defect.
Instead, the plaintiffs claim that the manufacturer was too slow in developing a different compound, tenofovir alafenamide (“TAF”), which they allege has a better safety profile. The FDA approved TAF-based products in 2015, but in the plaintiffs’ telling, the purported delay in developing these alternative therapies was unreasonable. Of course, in reality there was no “delay” at all, but merely a manufacturer’s decision to dedicate limited development resources to a product that ended up saving thousands of lives. Product manufacturers make product development decisions like these almost every day.
The trial court denied summary judgment on negligence, and the California Court of Appeal affirmed in an opinion that came in as our worst drug or medical device case of 2024. In a first-of-its-kind opinion, the Court of Appeal ruled that a pharmaceutical manufacturer has a duty of reasonable care when it has invented “what it knows is a safer, and at least equally effective, alternative to a prescription drug that it is currently selling and that is not shown to be defective.” Gilead Tenofovir Cases, 98 Cal.App.5th 911, 922 (2024).
The Court of Appeal basically purported to create a new tort—a claim sort of like negligence, but requiring “knowledge,” and custom designed to allow judges and juries to second guess isolated product development decisions, sometimes decades after the fact. This is all in the absence of any allegation of any product defect, let alone proof. Worse yet, the court drew an analogy to Mexicali Rose v. Superior Court, where the California Supreme Court held that a restaurant could be liable in negligence for a chicken bone found in an enchilada. Development of prescription medicines is not like cooking chicken enchiladas.
So here we are. The California Supreme Court granted the manufacturer’s petition for review, and oral argument is set for Wednesday, May 6, 2026, at 9:00 Pacific. The argument will be heard in the Supreme Court’s courtroom in San Francisco, with live-streaming available on the Supreme Court’s website. (Viewing California Supreme Court arguments can be a bit wonky, but if you scroll down to the Oral Arguments section and click through, you should be okay.)
Several critical issues are likely to dominate the argument. First, the Court will confront the threshold question of whether a negligence claim against a product manufacturer can proceed in the absence of any allegation that the product was defective. This question implicates the relationship between strict product liability and negligence, which have traditionally shared a common requirement of proving a product defect. That requirement goes back to the earliest days of product liability law in California and elsewhere.
Second, the Court will likely probe the boundaries of any duty it might recognize. The Court of Appeal attempted to characterize its holding as “narrow,” but we don’t buy it. The Court of Appeal’s attempt to define the purported duty was tortured at best, and the potential for confusion and slippery expansion clearly exists.
Third, public policy implications are obvious. In Brown v. Superior Court, 44 Cal. 3d 1049 (1988), the California Supreme Court rejected strict product liability for prescription drugs in part because public policy favors the development and marketing of beneficial new drugs. The Court of Appeal’s new duty directly undermines this precedent. Moreover, the Court of Appeal’s new duty potentially impacts not only pharmaceutical manufacturers, but also manufacturers in other industries driven by innovation. The International Center for Law & Economics argued in its amicus brief that the Court of Appeal’s rule effectively “imposes unlimited liability” by eliminating the defect requirement that has long served as a cornerstone of product liability law.
If the California Supreme Court affirms the Court of Appeal, it will establish a new theory of manufacturer liability that has no precedent in any American jurisdiction. If the Court reverses, it will reaffirm the centrality of the defect requirement to product liability law and retain potential negligence liability within well-established limits.
All eyes will be on San Francisco on May 6.