backOn May 6, 2026, the California Supreme Court heard oral argument in Gilead Tenofovir Cases, No. S283862, a case that could fundamentally reshape product liability law and the life sciences industry by imposing a “duty to innovate” on pharmaceutical manufacturers. Specifically, the case asks whether a manufacturer owes a duty to users of a non-defective medicine when making decisions on the development of an allegedly safer, alternative compound.
Approximately 24,000 users of Gilead Sciences’ HIV medicine tenofovir disoproxil fumarate (“TDF”) sued Gilead after allegedly experiencing side effects from the medication. The patients do not make traditional claims that TDF was unreasonably dangerous or defective. Instead, they allege that Gilead unreasonably delayed developing a similarly effective but potentially safer compound, tenofovir alafenamide (“TAF”), to maximize profits from its existing TDF patent protection.
In a first-of-its-kind opinion, the Court of Appeal allowed the theory to proceed, holding that a manufacturer’s duty to exercise reasonable care “can extend beyond the duty not to market a defective product.” The California Supreme Court granted review two years ago in May 2024 and heard argument on May 6, 2026.
The Court’s questioning suggested it was uncertain about the practical limits and broader implications of using tort law to impose a duty to innovate.
Key Arguments
At oral argument, the plaintiffs’ central theme was “profits over people”—that Gilead chose to prioritize revenue from TDF rather than bring a known safer alternative to patients. Plaintiffs argued that regardless of TAF’s efficacy and safety profile, Gilead delayed TAF’s release to coincide with the expiration of TDF’s patent. Plaintiffs framed their claim as a straightforward application of the general duty under California Civil Code Section 1714 to exercise reasonable care, arguing Gilead had “already invented” TAF and simply chose to withhold it.
Gilead countered that no court in California or any other jurisdiction has ever held a manufacturer liable for injuries caused by a non-defective product. Gilead also challenged plaintiffs’ claim that TAF was known to be safer than TDF at the time the decision was made to prioritize TDF. At the time the decision was allegedly made to prioritize TDF, only one Phase I/II human trial for TAF had been completed—involving just 20 patients who took TAF for a mere 14 days—and it found that TAF and TDF had “similar” safety profiles. TAF never advanced to Phase III clinical trials before Gilead stopped its development. Gilead warned that a ruling against it would cause pharmaceutical companies to alter their drug development behavior to avoid future liability—foregoing studies to avoid acquiring knowledge of safer alternatives, declining to bring improved products to market, and disincentivizing innovative research.
Signals from the Bench
The justices’ questioning signaled skepticism of the Court’s practical ability to enforce a duty to innovate and concern about the policy implications of upholding such a duty. The Court pressed the plaintiffs on what “negligence” means in this context—specifically, what standard of conduct a manufacturer would be measured against when no product defect is alleged. The justices also questioned whether prioritizing drug candidates is fundamentally a policy question better addressed by the legislature.
Implications
This case carries significant implications for the pharmaceutical industry. If the Court affirms, drug manufacturers could face negligence liability for injuries allegedly caused by non-defective products—opening the door for patients to argue that, in hindsight, the manufacturer should have marketed a different product sooner. Various amici warned that this liability framework would chill R&D investment, subject complex scientific and business decisions to hindsight scrutiny by lay juries decades later, and ultimately result in fewer new products reaching consumers. If the Court reverses, it will reaffirm the well-settled principle that product liability claims require proof of a product defect, providing important certainty for manufacturers across all industries.
The California Supreme Court typically issues its opinion within 90 days of oral argument but has not said when it will rule in this case. We will continue to monitor case developments.