A panel of the U.S. Court of Appeals for the Ninth Circuit on Friday appeared unlikely to reverse an $80 million Roundup verdict based on federal preemption, but at least one jurist questioned whether expert evidence allowed at trial set the appellate court apart from the rest of the country.

In arguments that stretched to double the allotted time, the panel focused largely on a 2019 letter that the U.S. Environmental Protection Agency sent to several manufacturers, including Monsanto Co., concluding that any label warning about cancer risks on their pesticides would be false and misleading and violate federal law. Under the U.S. Supreme Court's Merck Sharp & Dohme v. Albrecht decision in 2019, according to Monsanto's lawyers, the letter had the "binding force of law" to prevent the company, now owned by Bayer, from adding the warning label that lawyers for plaintiff Edwin Hardeman insisted should have been on Roundup.