One of the claims most commonly raised in pesticide injury cases is the claim of negligence. Like the other claims discussed in this series, negligence is a state law claim derived from common law. Plaintiff raise claims of negligence to argue that they have been injured due to the defendant’s failure to act in a reasonable manner. In pesticide injury cases, plaintiffs tend to claim that the defendants were negligent in manufacturing and marketing their products.

What is Negligence?

Negligence claims raised in pesticide injury lawsuits fall into the category of laws known as torts. A tort is generally defined as an action by one party that results in injury or harm to another party for which a court may impose liability. There are many different types of civil torts, several of which will be explored in this series.

The tort of negligence is typically described as the failure to behave with the level of care that a reasonable person in the same set of circumstances would have exercised. Oftentimes this behavior is an action, but it can also be an omission when there is a duty to act.

There are four elements required to establish whether a defendant was legally negligent. First, there must exist a legal duty that the defendant owed to the plaintiff. Second, the defendant must have breached that duty. Third, the plaintiff must have suffered a harm or injury. Finally, that harm or injury must have been caused by the defendant’s breach of duty (this is typically referred to as “proximate cause”). For example, each driver on the road has a duty to exercise reasonable care in order to not injure other drivers, passengers, or pedestrians. If a driver fails to exercise this duty to act with reasonable care, perhaps by driving unreasonably fast or while intoxicated, the driver will be considered in breach of the duty. If the breach results in injury to another person, then the driver would likely be found negligent.

Negligence Arguments in Pesticide Lawsuits

Plaintiffs in pesticide injury lawsuits almost always bring negligence claims against the defendant pesticide manufacturer. For the most part, these claims are largely similar. Plaintiffs allege that the defendants failed to behave as a reasonable pesticide manufacturer would have in similar circumstances, leading to a breach of the duty of care owed to consumers, and ultimately causing plaintiffs to suffer injuries. However, plaintiffs have differed on what specific behaviors they claim breached the duty of care. The following is an overview of some of the negligence arguments raised by pesticide injury plaintiffs.

One of the earliest pesticide injury lawsuits was filed in 2016 by a plaintiff alleging that exposure to the glyphosate-based pesticide Roundup caused him to develop non-Hodgkin’s lymphoma. In Hardeman v. Monsanto Co., No. 4:16-cv-00525 (N.D. Cal.), negligence is the first claim the plaintiff raised in his complaint. According to the plaintiff, the defendant had failed to act with the duty of care expected of a reasonable pesticide manufacturer to produce a product that would not cause users to suffer dangerous side effects. Actions the plaintiff highlighted as negligent include: failing to thoroughly test the effects of Roundup on humans; failing to warn the public of the dangers of Roundup; failing to provide adequate warnings to protect the health of Roundup users; and marketing Roundup as safe for use when the defendant either knew or should have known that exposure to Roundup could result in harm. The plaintiff claims that if the defendant had acted as a reasonable pesticide manufacturer, by conducting adequate tests, including appropriate warning labels, or including the dangers of Roundup in its marketing, then the plaintiff would not have suffered an injury.

Many of the actions highlighted by the plaintiff in Hardeman v. Monsanto Co. as negligent were identified by other glyphosate plaintiffs as well. For example, in In re: Roundup Products Liability Litigation, No. 3:16-md-02741 (N.D. Cal.), the multi-district litigation involving hundreds of glyphosate plaintiffs, the complaint claims that the defendant negligently failed to appropriately test Roundup, failed to provide adequate warnings to the public and to users of Roundup, and marketed Roundup as safe for use. Additionally, the plaintiffs in In re: Roundup Products claimed that the defendant negligently failed to share the results of the tests it did conduct on human exposure to glyphosate, and failed to test the “inert” ingredients in Roundup to determine whether Roundup as a product was more toxic than glyphosate on its own. Like the plaintiff in Hardeman v. Monsanto, the plaintiffs in In re: Roundup Products alleged that if the defendant had acted like a reasonable pesticide manufacturer, then the plaintiffs’ injuries would not have occurred.

Plaintiffs in lawsuits concerning pesticides other than glyphosate have also raised negligence claims. In both Avila v. Corteva Inc., No. 20C-0311 (Cal. Sup. Ct.), and Calderon de Cerda v. Corteva Inc., No. 20C-0250 (Cal. Sup. Ct.), plaintiffs claiming injuries as the result of exposure to chlorpyrifos alleged that the defendant breached its duty of care to develop a safe product. Similar to the glyphosate lawsuits, the plaintiffs in the chlorpyrifos lawsuits allege that the defendant was negligent due to a failure to appropriately test the effects of its chlorpyrifos-based pesticide Lorsban on humans. Additionally, the chlorpyrifos plaintiffs claim that the defendant negligently marketed Lorsban without adequate warnings as to how chlorpyrifos affects children. Plaintiffs in Hoffman v. Syngenta Crop Protection, LLC, No. 17-L-517 (Ill. Cir. Ct.) also claimed that the defendant was negligent in its manufacture and marketing of the pesticide paraquat. According to the paraquat plaintiffs, the defendant negligently designed and sold a pesticide that could be inhaled or absorbed into the bodies of users where it would ultimately cause neurological damage. The plaintiffs also claimed that the defendant breached its duty of care by failing to adequately test the effects of its product or warn consumers that its product was dangerous.

Overall, plaintiffs in pesticide lawsuits tend to focus on three broad issues when raising negligence claims: failure to conduct appropriate testing of the pesticide; failure to warn users and the public of dangers associated with using the pesticide; and marketing a pesticide as safe to use. According to the plaintiffs, these actions are all breaches of the defendants’ duty to act as a reasonable pesticide manufacturer and develop a safe product.

Treatment by Courts

So far, the negligence claims in pesticide injury cases that have made it to a jury trial have received mixed results. The first three glyphosate lawsuits to go to trial, Hardeman v. Monsanto Co., Pilliod v. Monsanto Co., No. RG17862702 (Cal. Sup. Ct.), and Johnson v. Monsanto Co., No. CGC-16-550128 (Cal. Sup. Ct.), resulted in jury verdicts that found the defendant had been negligent by failing to adequately test the effects of Roundup and in marketing the product as safe to use. When the defendant appealed the Pilliod v. Monsanto Co. decision, the appellate court denied to hear the appeal. According to the appellate judges, there was enough evidence for the jury to find that the defendant had failed to test Roundup in a manner consistent with what a reasonable pesticide manufacturer would have done.

However, two other glyphosate lawsuits that went to trial in 2021 resulted in decisions favorable to the defendant. In both Stephens v. Monsanto Co., No. CGC-20-585764 (Cal. Sup. Ct.), and Clark v. Monsanto Co., No. 20STCV46616 (Cal. Sup. Ct.), juries concluded that there was not enough evidence to show that exposure to Roundup caused the plaintiffs to develop cancer. In those cases, the jury did not find that the defendant was negligent.

Of the thousands of pesticide injury lawsuits filed over the past several years, so far only glyphosate lawsuits have gone to trial. From the decisions reached in those lawsuits, it is clear that some juries have been convinced by the plaintiffs’ claims of negligence while others have not.


Despite receiving mixed treatment by the courts, plaintiffs in pesticide injury cases are likely to continue raising claims of negligence in their complaints. While other claims that will be explored in this series are more narrow, and describe more specific behavior, negligence claims are rather broad. Plaintiffs have used negligence claims to target a wide variety of activities from the defendants, through the entire manufacture and marketing process. Negligence will likely continue to drive pesticide injury lawsuits.


To read the complaint in Hardeman v. Monsanto Co., click here.

To read the complaint in In re: Roundup Products, click here.

To read the complaint in Avila v. Corteva Inc., click here.

To read the complaint in Calderon de Cerda v. Corteva Inc., click here.

To read the complaint in Hoffman v. Syngenta Crop Protection, LLC, click here.

To read the appellate court’s decision in Pilliod v. Monsanto Co., click here.

To read the previous post in this series, click here.

For more resources on pesticide regulation from the National Agricultural Law Center, click here.