On August 10, 2018, a jury in the Superior Court of California, San Francisco County, unanimously rules that Roundup, manufactured by Monsanto, induced Dewayne Johnson's non-Hodgkin's lymphoma (NHL). The company was found guilty of design and warning defects, negligence and breach of implied warranties, and ordered to pay $290 million in damages, including $250 million in punitive damages. The U.S. Environmental Protection Agency's (EPA) approval of glyphosate did not prevent a victim of personal injury from seeking damages from a company at fault.

Dewayne Lee Johnson was in charge of pest control at a school northeast of San Francisco. He used Roundup, then RangerPro, which he had to dilute in hundreds of liters of water before spraying. On two occasions, he was sprayed with these products because of malfunctioning sprayers. By virtue of a Californian law which obliges courts to organize proceedings before the plaintiff's death, his trial is one of the first to recognize Monsanto's no-fault criminal liability. His doctors estimated his life expectancy at the time at 2 years.

On September 18, 2018, Monsanto asked the judge to set aside the verdict, order a new trial, or alternatively, reduce the amount of damages, pointing to the lack of evidence to support the plaintiff's allegations and the "flagrant misconduct before the jury" of attorney Brent Wisner. On October 22, 2018, the judgment was upheld on the merits, but the amount of punitive damages is reduced from $250 million to $39 million. The plaintiff accepts the decision on October 26, 2018. Otherwise, Monsanto's motion for a new trial would have been automatically granted.

On November 20, 2018, Monsanto appeals the judgment. Dewayne Lee Johnson also cross-appeals, seeking reinstatement of the full original award. On July 20, 2020, the Court of Appeal declared Monsanto's arguments unconvincing and upheld the verdict on the merits. However, damages are again reduced to $20.5 million. On August 4, 2020, Monsanto and Dewayne Johnson both requested a review of the verdict by the California Supreme Court. Dewayne Johnson sought reinstatement of the jury's $250 million punitive damages award. Monsanto, for its part, asked the California Supreme Court to reverse the state Court of Appeal's decision. On October 21, 2020, the California Supreme Court denied the requests.