Gilead Sciences, Inc. developed tenofovir disoproxil fumarate (TDF), an HIV antiretroviral medication marketed as Viread and used in numerous combination HIV therapies, obtaining FDA approval in October 2001. While TDF was still in trials, Gilead began investigating a related compound, tenofovir alafenamide fumarate (TAF), as a possible backup. A brief 2001 phase I/II trial — 30 subjects over two weeks — suggested TAF could match TDF’s antiviral effect at a much lower dose, potentially with less kidney, bone, and tooth toxicity. In 2004, Gilead announced it was discontinuing TAF development, stating TAF’s profile did not appear meaningfully different from TDF’s. Plaintiffs, a large group of TDF users who allege they developed renal, bone, or tooth injuries from the drug, contend Gilead’s stated reason was pretextual and that Gilead actually shelved TAF to protect TDF sales and later timed TAF’s eventual release to extend patent-driven profits across both drugs. Gilead disputes that it knew TAF was safer at the time and says it resumed TAF development in 2010 to address bone and kidney concerns in an aging HIV population, ultimately winning FDA approval for TAF in November 2015. Plaintiffs do not contend TDF itself is defective, and they acknowledge some patients still prefer TDF to TAF; their theory is that Gilead’s delay in developing and commercializing TAF was itself negligent and caused their injuries.
By the time Gilead moved for summary judgment, only negligence and fraudulent concealment claims remained. The San Francisco County Superior Court denied summary judgment on both. Gilead petitioned for a writ of mandate, and the Court of Appeal granted the petition as to the fraudulent concealment claim but left the negligence claim intact, holding in a published 2024 decision that a drug manufacturer’s duty of reasonable care can, in some circumstances, extend beyond the duty to avoid marketing a defective product — specifically, that a manufacturer who has invented a drug it knows to be safer and at least equally effective than one it is currently selling may owe a duty of reasonable care regarding when to commercialize it. (Gilead Tenofovir Cases (2024) 98 Cal.App.5th 911.) The Court of Appeal further held the foreseeability and public-policy factors from Rowland v. Christian did not support an exception to that duty on the record before it.
In the case of Gilead Tenofovir Cases, No. S283862 (Cal. Sup. Ct., August 2026) — the California Supreme Court reversed the judgment of the Court of Appeal and remanded with directions to grant summary judgment for Gilead on all remaining causes of action. Chief Justice Guerrero and Justice Kruger (joined by Justices Corrigan and Desautels) each filed separate concurring opinions; Justice Evans filed a dissent
Writing for the majority, Justice Groban expressed “significant doubt” that California law recognizes a manufacturer’s negligence duty independent of a product defect at all, noting decades of precedent tying a manufacturer’s duty under Civil Code section 1714 to the duty to design, manufacture, and market products free from defects, citing Merrill v. Navegar, Inc. (2001) 26 Cal.4th 465. But the majority found it unnecessary to resolve that threshold question. Even assuming a broader duty could exist, the Court held that the foreseeability and public-policy factors from Rowland v. Christian (1968) 69 Cal.2d 108 compel an exception to it here, applied “categorically” rather than to Gilead’s specific case, consistent with Kuciemba v. Victory Woodworks, Inc. (2023) 14 Cal.5th 993.
On foreseeability, the majority held a manufacturer generally cannot reliably know, based only on early-phase clinical data, that an alternative drug is in fact safer than and as effective as an existing one; the Food, Drug, and Cosmetic Act itself generally requires two adequate, well-controlled studies (typically phase III trials) before FDA approval, and only about 25 to 30 percent of drugs that reach phase III succeed. Because that comparative knowledge is essentially unattainable during the early development stages at issue here, the Court held harm to existing-drug users was not reasonably foreseeable from a decision to pause a still-unproven alternative, and separately found the causal chain from that decision to any eventual injury too attenuated, given the intervening, independent, and uncertain decisions of regulators, physicians, and patients that stand between a development decision and any patient’s actual treatment.
On the public-policy factors, the majority found moral blame difficult to assess categorically, since manufacturers may delay developing a backup drug for many morally neutral reasons, including allocating resources toward diseases with no existing treatment; found the policy of preventing future harm cut both ways, since a duty could speed development of safer alternatives but could equally distort research priorities, discourage manufacturers from investigating backup candidates at all, or push manufacturers to delay releasing improved drugs until every conceivable alternative has been fully vetted; and found the burden on manufacturers substantial, since phase III trials alone can cost tens of millions of dollars and take years, with no guarantee of eventual approval. The Court noted Gilead’s own estimate that completing TAF’s remaining development would cost roughly $100 million. Taken together, the majority held drug manufacturers owe no duty of care, when deciding whether and when to develop and commercialize an allegedly safer alternative, to users of a current, concededly nondefective drug — while emphasizing the ruling does not immunize manufacturers from ordinary defect, failure-to-warn, or fraud-based claims.
Chief Justice Guerrero concurred in the result but not the reasoning, arguing the majority should not have assumed a broader duty of care exists at all. In her view, decades of settled products liability law establish that a defect is an essential element of any negligence claim against a manufacturer, citing Jiminez v. Sears, Roebuck & Co. (1971) 4 Cal.3d 379, and because plaintiffs expressly disclaimed any allegation that TDF was defective, their claim should have failed on that threshold ground without needing to reach Rowland’s foreseeability or policy factors at all. Justice Kruger, joined by Justices Corrigan and Desautels, separately concurred to elaborate on aspects of the majority’s Rowland analysis. Justice Evans dissented, arguing the majority’s application of Rowland effectively guaranteed the outcome by treating the manufacturer’s own alleged profit motive and superior knowledge as insufficient to establish moral blame, and characterizing the majority’s holding as granting drug manufacturers sweeping immunity from liability for delay-driven development decisions.