DUTY TO WARN: HOW COURTS INTERPRET RESPONSIBILITY IN DRUG AND DEVICE CASES
Duty to warn in pharmaceutical and medical‐device litigation remains one of the most contested battlegrounds in product liability. In 2025, courts continue to wrestle with the tension between state tort law and federal regulation, especially in areas of preemption, postmarket warning updates, and causation burdens under the learned intermediary doctrine. Below are several illustrative developments, and the evolving judicial approach to duty to warn claims.
Key 2025 Developments & Cases
1. Preemption and the Limits on Label Change Authority
In In re: Gardasil Products Liability Litigation (W.D.N.C., Mar. 11, 2025), the court granted summary judgment in favor of Merck on failuretowarn claims based on federal labeling preemption, emphasizing that the company could not unilaterally change its label without “newly acquired information” that meets the regulatory standard for causation.
Plaintiffs alleged risks of POTS (postural orthostatic tachycardia syndrome) and POI (primary ovarian insufficiency). The court concluded that the evidence (a few case reports, adverse event reports) was insufficient to establish a “causal association” under 21 C.F.R. § 201.57(c)(6)(i), and thus did not permit a label change under the CBE (“Changes Being Effected”) regulation.
Because Merck lacked authority to unilaterally impose stronger warnings beyond those approved by FDA, state law claims requiring such changes were held preempted.
The court’s methodology that was working backward from the regulatory threshold for causal association before reaching preemption, is instructive for how courts in 2025 approach duty to warn challenges.
This decision reinforces that even where plaintiffs argue new risks discovered postapproval, courts will closely scrutinize whether the “newly acquired information” truly meets regulatory requirements before finding a duty to strengthen warnings.
2. DepoProvera Litigation & Preemption Battles
In August 2025, Pfizer moved to dismiss multiple failure to warn claims in the DepoProvera MDL, contending that FDA had already rejected its pitch to include warnings about meningioma tumors and thus state claims are preempted. IN RE: DepoProvera Products Liability Litigation (MDL No. 3:25md03140)
Plaintiffs alleged that Pfizer possessed long‐standing scientific evidence linking DepoProvera to meningiomas which it failed to disclose. But Pfizer’s defense is that the FDA in 2023 denied the label change request for brain tumor risk due to insufficient data, and so federal law precludes state imposition of warnings not approved by FDA. The MDL scheduling order anticipates full preemption briefing and oral argument by late September 2025.
This conflict highlights a recurring theme in 2025, which is plaintiffs push for expanded warnings based on evolving science, while defendants rely on FDA’s regulatory judgments and the doctrine of preemption to shield themselves.
3. Warner v. Amgen — Learned Intermediary & Causation
In Warner v. Amgen Inc., 2025 U.S. Dist. LEXIS 26141 (D. Mass. Feb. 13, 2025), the court addressed a claim that a migraine drug’s labeling omitted warnings for excluded populations (those with prior seizures or cerebrovascular disease). The court held that both the preapproval and the postapproval failure to warn claims were preempted. While the preapproval claims were preempted because FDA had been aware of the exclusion criteria and did not require their labeling, Postapproval claims failed because plaintiff could not allege proper “newly acquired information” to permit a CBE label strengthening.
On summary judgment, the court also emphasized that under Massachusetts law and applicable choice rules, the learned intermediary standard applied, and plaintiff offered no affirmative evidence that a stronger warning would have changed a physician’s conduct, a deficiency fatal to causation.
Notably, in some jurisdictions (like Colorado), there is no “heeding presumption” under learned intermediary law. Plaintiffs must prove what the physician would have done with better warnings.
Warner underscores that even when plaintiffs argue omissions in labeling, causation under the learned intermediary doctrine remains a critical hurdle.
4. Device Case: Tandem Diabetes Pump & Preemption
In Gallego v. Tandem Diabetes Care, Inc., No. 1:2024cv00146 (E.D.N.Y. May 31, 2025), the court dismissed failure to warn claims concerning an insulin pump, holding that plaintiff did not state a “parallel” claim under state law that would survive preemption scrutiny.
The complaint alleged numerous design, labeling, and warning failures, but the court found that plaintiff did not allege violation of any FDA label requirement or a state duty parallel thereto. Because placing additional or stronger labeling obligations beyond what FDA required would conflict with federal law, the state claims were dismissed.
This case illustrates the precise pleading demands in device warning claims when federal preemption looms.
Given these developments, several themes emerge about how courts in 2025 are interpreting “duty to warn” in the drug and device context:
- Preemption continues to dominate the terrain
Many failure to warn claims in regulated products face motions to dismiss or summary judgment based on the doctrine that state law cannot impose labeling obligations inconsistent with federal law. Gardasil and Warner are emblematic of this trend.
- “Newly Acquired Information” remains a gatekeeper
Plaintiffs seeking to force label changes postapproval must carefully satisfy regulatory thresholds (e.g. under CBE) showing reasonable evidence of causation. Courts are increasingly strict and require a strong factual showing.
- Causation under the learned intermediary doctrine is still fatal in many cases
Plaintiffs must present affirmative evidence that a better warning would have altered physician behavior. Courts in 2025, like in Warner, deny relief when parties fail to depose or question treating physicians on this point.
- Strict pleading and parallel duty requirements in device cases
For medical devices, plaintiffs must allege that the manufacturer violated a duty as strict as the FDA rule itself (a “parallel claim”) to avoid preemption dismissal, as seen in Gallego v. Tandem.
By late 2025, courts have increasingly tightened the framework governing duty to warn claims in drug and device litigation. The combination of preemption doctrines, stringent regulatory standards for label changes, and demanding causation proof under the learned intermediary doctrine means plaintiffs face steep hurdles in crafting viable claims. At the same time, defense strategies grounded in FDA decision authority and regulatory consistency continue to find traction.
That said, tensions remain unresolved, particularly around evolving risks discovered postmarket and how courts should weigh them against federal constraints. The outcome of the upcoming preemption hearing in the DepoProvera MDL (scheduled for September 2025) may become a telling bellwether for how much space remains for state failure to warn claims in the regulatory era.