Monsanto GMO Lawsuits: Roundup, Dicamba, and PCB Claims

Monsanto lawsuits span four decades and several distinct fights: tens of thousands of claims that Roundup causes non-Hodgkin lymphoma, dicamba drift damage cases brought by farmers whose crops were harmed by neighbors’ spraying, PCB contamination suits from cities and states, and older patent enforcement actions against farmers who saved genetically modified seed. Bayer, which bought Monsanto in 2018 for $63 billion, has already paid over $11 billion resolving Roundup claims and still faces roughly 65,000 pending cases.¹

Roundup Cancer Lawsuits

The largest and most active line of litigation involves Roundup, the world’s most widely used herbicide. Plaintiffs allege that glyphosate, its active ingredient, causes non-Hodgkin lymphoma. The scientific record is split: the World Health Organization’s International Agency for Research on Cancer classified glyphosate as “probably carcinogenic to humans” in 2015, while the U.S. Environmental Protection Agency has maintained that glyphosate does not cause cancer.² That disagreement has powered years of jury trials on both sides of the country.

The First Three Trials

DeWayne Johnson, a former school groundskeeper diagnosed with non-Hodgkin lymphoma, brought the first Roundup case to trial. On August 10, 2018, a San Francisco jury awarded him $289 million, including $250 million in punitive damages. The trial court later required Johnson to accept a reduction to roughly $39.3 million as a condition of denying a new trial, and a California appellate court affirmed liability in July 2020 while ordering further cuts to the damages.³⁴

Edwin Hardeman’s case served as the bellwether in the federal multidistrict litigation in the Northern District of California. In March 2019, a jury awarded him about $5.3 million in compensatory damages and $75 million in punitive damages; the trial judge reduced the punitive award to $20 million. The Ninth Circuit affirmed the $25.3 million judgment in May 2021, rejecting Monsanto’s argument that federal pesticide labeling law preempted state failure-to-warn claims. The Supreme Court declined to review the case in June 2022.⁵⁶

The third early trial produced the largest headline number. In May 2019, an Alameda County jury awarded Alberta and Alva Pilliod a combined $2.055 billion after finding Roundup caused both of their lymphoma diagnoses. The trial court cut the award to about $56 million for Alberta and $31 million for Alva as conditions for denying a new trial, and the California Court of Appeal affirmed in August 2021.⁷

Recent Verdicts

Trials have continued to produce large numbers, though judges frequently reduce them. In November 2023, a St. Louis jury awarded four plaintiffs $1.56 billion; a separate Missouri jury awarded $1.25 million; and a California jury returned a $332 million verdict. In January 2024, a Pennsylvania jury awarded $2.25 billion, later reduced by a judge to $400 million. A Philadelphia jury awarded $78 million in October 2024.⁸

In March 2025, a Cobb County, Georgia jury awarded John Barnes nearly $2.1 billion, consisting of $65 million in compensatory damages and $2 billion in punitive damages. Bayer filed a motion for judgment notwithstanding the verdict and said it will appeal.⁹¹⁰ Bayer has also won some trials outright, including defense verdicts in September and November 2024.⁸

The $7.25 Billion Class Settlement

In February 2026, Bayer and a group of plaintiffs’ lawyers announced a proposed $7.25 billion national class settlement to resolve current and future Roundup lymphoma claims. A Missouri judge granted preliminary approval in March 2026. Eligible claimants would receive estimated payments of $10,000 to $165,000 based on exposure history and age at diagnosis. Bayer does not admit liability.²

The deal has drawn hard opposition. Federal Judge Vince Chhabria, who oversees the Roundup MDL in California, called the settlement “filthy” and “mind-boggling” during an April 2026 hearing, criticizing the secretive process through which it was presented to the Missouri court. A group of 14 law firms representing nearly 20,000 potential class members sought to intervene, arguing the class definition was too broad and the opt-out procedures were onerous.¹ In June 2026, a federal judge remanded the settlement back to Missouri state court after ruling that objecting plaintiffs lacked authority to move it to federal court. Those objectors have filed a notice of appeal.¹¹

The Supreme Court Preemption Case

Hanging over everything is Monsanto Co. v. Durnell, which the Supreme Court agreed to hear in January 2026. The question is whether the Federal Insecticide, Fungicide, and Rodenticide Act preempts state failure-to-warn claims when the EPA has not classified glyphosate as carcinogenic. Monsanto argues federal law demands uniform pesticide labeling and that the company cannot unilaterally add cancer warnings that contradict the EPA’s position. Respondents counter that EPA registration is only preliminary evidence of compliance and does not immunize manufacturers from state tort claims.¹²

Oral arguments on April 27, 2026 revealed a divided bench, with several justices questioning why states should be unable to act when the EPA’s review process moves slowly and others pressing on how labels could remain uniform if every state imposed different requirements. The federal government filed an amicus brief supporting Monsanto. A decision is expected by early July 2026, and a ruling in Bayer’s favor could dismiss or limit a significant share of the roughly 65,000 pending cases.¹²¹¹

Bayer’s Exposure and the Bankruptcy Option

Beyond the $11 billion already paid, Bayer has reportedly explored filing for Chapter 11 bankruptcy for its Monsanto subsidiary to isolate the mass tort liabilities. As of mid-2026, the company is prioritizing the class settlement and holding bankruptcy as a contingency if that deal fails.¹³ To reduce future exposure, Bayer began reformulating its residential Roundup products with different active ingredients in 2023, though agricultural and professional products still use glyphosate.¹⁰

Dicamba Drift Lawsuits

A separate wave of litigation arose from Monsanto’s dicamba-tolerant “Xtend” crop system. USDA deregulated Xtend cotton seeds in 2015 and Xtend soybeans in 2016, but EPA-approved dicamba formulations designed for over-the-top application weren’t available until later. Farmers who planted the resistant crops used older, more volatile dicamba formulations, causing widespread drift damage to neighboring fields.¹⁴

The landmark case came from Bader Farms, a Missouri peach orchard alleging that dicamba drift destroyed its crops between 2015 and 2019. In February 2020, a federal jury awarded Bader Farms $15 million in actual damages and $250 million in punitive damages against Monsanto and BASF. The trial court reduced the punitive award to $60 million. On appeal, the Eighth Circuit upheld the liability findings and the finding of a civil conspiracy between Monsanto and BASF but vacated the punitive damages, ruling that punitive amounts should have been assessed against each defendant separately under Missouri law. Monsanto later settled with Bader Farms.¹⁵¹⁶

Claims from across the Midwest and South were consolidated as In re: Dicamba Herbicides Litigation in the Eastern District of Missouri. In 2022, Bayer offered up to $400 million to settle dicamba-related claims, and the MDL was formally terminated in October 2025.¹⁷

On the regulatory side, the Ninth Circuit in June 2020 vacated the EPA’s 2018 conditional registrations for three dicamba herbicides: XtendiMax (Bayer), Engenia (BASF), and FeXapan (Corteva). The court found the EPA had substantially understated drift risks and ignored evidence that even careful farmers struggled to follow the complex label instructions. The EPA then issued a cancellation order allowing limited use of existing stocks through July 31, 2020.¹⁸¹⁹

PCB Contamination Suits

Monsanto produced polychlorinated biphenyls from 1935 to 1977, when the chemicals were banned in the United States due to links to cancer and other health problems. Decades later, cities, states, and individuals began suing over the consequences.

In June 2020, Bayer announced a $650 million class settlement with approximately 2,500 municipalities over PCB-contaminated stormwater systems; the settlement received final court approval in November 2022.²⁰ Monsanto has also settled with attorneys general in at least 12 states, including agreements with Illinois worth up to $280 million and with West Virginia worth up to $60.5 million, both announced in December 2025.²¹ As of mid-2026, cases remain pending with the attorneys general of Delaware, Maine, Maryland, New Jersey, and Vermont.²²

Personal injury claims have also come from more than 200 plaintiffs alleging PCB exposure at the Sky Valley Education Center in Washington. Ten trials had taken place by early 2025, and Bayer settled the lead case on confidential terms in December 2025. School districts in Vermont and North Carolina have filed separate property damage claims.²²

Seed Patent Cases Against Farmers

Monsanto built its position in agricultural biotech largely through “Roundup Ready” seeds engineered to survive glyphosate. The company sold them under a Technology Agreement restricting farmers to a single growing season and prohibiting saving harvested seed for replanting.²³ Monsanto enforced those restrictions hard. According to a report cited by The Guardian, the company filed roughly 142 patent infringement lawsuits targeting 410 farmers and 56 small businesses in more than 27 states, recovering over $23 million.²⁴ Hundreds more disputes settled out of court.

The highest-profile case reached the U.S. Supreme Court in 2013. Indiana farmer Vernon Hugh Bowman bought commodity soybeans from a local grain elevator for late-season planting, sprayed the resulting crop with glyphosate to isolate the Roundup Ready survivors, and replanted them across several seasons. In a unanimous decision by Justice Elena Kagan on May 13, 2013, the Court held that patent exhaustion does not permit buyers to make new copies of a patented invention; by planting and harvesting, Bowman had effectively manufactured additional copies. The $84,456 damages award stood.²³²⁵

The Canadian parallel was Monsanto v. Schmeiser. Saskatchewan farmer Percy Schmeiser said Roundup-resistant canola arrived on his land accidentally, but after finding surviving plants near power poles he harvested, stored, and replanted the progeny across roughly 1,000 acres in 1998. The trial court ruled for Monsanto in 2001; the Federal Court of Appeal upheld in 2002; and the Supreme Court of Canada affirmed 5–4 in 2004. The courts never made a definitive finding on how the seed first reached the property.²⁶

Organic growers tried to head off future suits. In March 2011, the Organic Seed Growers and Trade Association and about 60 other groups filed suit in federal court in New York, seeking to invalidate 23 Monsanto patents and to bar the company from suing over inadvertent contamination. Judge Naomi Reice Buchwald dismissed the case in February 2012 for lack of standing. The Federal Circuit affirmed in June 2013, holding that Monsanto’s public statements and court representations amounted to a binding disclaimer of any intent to sue over “trace amounts,” which the panel defined as roughly one percent of a crop. The Supreme Court declined review in 2014.²⁷²⁸

GMO Labeling Fights

Monsanto also fought labeling requirements in court and at the ballot box. Beginning in 2012, the company spent more than $22 million opposing state labeling initiatives in California, Washington, Oregon, and Colorado; the broader agrichemical industry collectively spent over $103 million defeating those measures between 2012 and 2014.²⁹³⁰

When Vermont enacted the first mandatory labeling law in 2014, the Grocery Manufacturers Association sued in federal court to block it. Congress preempted the state-by-state approach in July 2016 with the National Bioengineered Food Disclosure Law, which allows manufacturers to satisfy labeling requirements through text, a symbol, or an electronic link such as a QR code, and overrides differing state laws.³¹³⁰

International Litigation

In Mexico, a 2020 presidential decree banned glyphosate and GM corn for human consumption. Monsanto’s Mexican subsidiaries filed over 30 amparo lawsuits challenging the decree and obtained a court order blocking its application in 2022. In June 2024, they withdrew those legal challenges. A December 2024 USMCA arbitration panel ruled in the U.S.’s favor on trade grounds, and Mexico modified the decree in March 2025 to allow GM corn in tortillas and other food products while maintaining its ban on GM corn cultivation and phase-out of glyphosate. President Claudia Sheinbaum signed a constitutional reform banning GM corn cultivation the same month.³²³³

In India, Monsanto’s fight was over Bt cotton, engineered to resist bollworm. After the Indian government capped seed prices and cut royalties in 2015, Monsanto terminated its sublicensing contract with Nuziveedu Seeds and filed a patent infringement suit. A Delhi High Court division bench declared Monsanto’s patent invalid in 2018 under a provision of Indian patent law that excludes seeds and essentially biological processes from patentability. In January 2019, the Supreme Court of India set that ruling aside, finding the High Court had exceeded its jurisdiction by deciding validity without a full trial, and remanded for proper proceedings. The patent expired in November 2019, mooting the injunction claim, though the damages question remains pending.³⁴³⁵³⁶

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