On December 5, 2017, John R. Carson, linking the malignant fibrous histiocytoma (MFH) he suffered from to his regular exposure for 30 years to the glyphosate he applied to his garden, the main ingredient in Roundup, manufactured by Monsanto Company, filed a lawsuit against Monsanto. The Georgia state law complaint alleges four counts: it alleges strict liability for failure to design (Count I), strict liability for failure to warn (Count II), negligence (Count III) and breach of implied warranties (Count IV).

In a decision issued on December 21, 2021, the Court for the Southern District of Georgia dismissed the plaintiff's claim, holding that the failure to warn (Count II) and breach of implied warranties (IV) claims were preempted under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA). The defendant's argument that if it had placed cancer warnings on its product labels, even though the U.S. Environmental Protection Agency (EPA), which has oversight over label language under FIFRA, had stated in its assessment that glyphosate was not likely to be a carcinogen and approved the Roundup label, it would have conflicted with the provisions of FIFRA, is thus upheld. In addition, the district court dismissed Counts I and III regarding strict liability, design defect, and negligence, as those claims related to the manner in which Roundup® was labeled or packaged.

Carson appealed only Count II, pursuant to a settlement agreement with the company that required him to dismiss Counts I and III. The issue for the appellate judges, therefore, was whether the district court erred in finding that Carson's failure-to-warn claim was preempted by FIFRA.

In a decision issued on July 12, 2022, the U.S. Court of Appeals for the 11th Circuit reversed and remanded. The Court ruled that John R. Carson's claim for failure to warn was not preempted by FIFRA. In doing so, it first recalled that FIFRA and EPA's actions under FIFRA may preempt state law only if the federal action has the force of law.

Regarding EPA's registration process for pesticide manufacturers seeking to market their products, the Court explains that it is not sufficiently formal to have the force of law (within the meaning of Mead) and therefore does not preempt state law. If EPA checks for violations of the labeling requirement on manufacturers' proposed labels during this process (e.g., a failure to provide adequate warnings or cautions to protect health and the environment), EPA may miss a mislabeled label during the registration process and the manufacturer may post facto report new health and environmental effects. Thus, a pesticide manufacturer cannot rely on EPA registration as a defense to a marketing ban violation under FIFRA.

With respect to FIFRA's statutory labeling requirements, a failure-to-warn action is preempted by FIFRA if (1) the state requirement is for labeling or packaging and (2) it is additional to or different from FIFRA's requirements cf. 7 U.S.C. § 136v(b). Yet, the Court of Appeals reveals that the failure to warn under Georgia common law is neither different from nor additional to any action taken by EPA that has the force of law. Rather, it imposes a less burdensome duty that focuses only on uninformed consumers of the dangerousness. FIFRA, on the other hand, imposes a general duty, regardless of the consumer's knowledge, where the warning is necessary to protect health and the environment. Thus, the Georgia failure-to-warn action merely applies the FIFRA cause of action, so it is not expressly preempted.

On December 19, 2022, the Court of Appeals granted Monsanto's petition for rehearing en banc. Under Eleventh Circuit Rule 35, the effect of granting rehearing en banc is to vacate the prior opinion and judgment of this court and to reverse the decision of the Court of Appeals.

Several amicus curiae briefs in support of both parties have been filed, including the NGO Public Citizen. It notes that Monsanto's overly broad interpretation of the scope of FIFRA, if adopted by this Court, would reduce the incentive for pesticide manufacturers to disclose safety risks and deny consumers redress for injuries they suffer due to exposure to inadequately warned pesticides.