San Francisco, CA—A federal jury in San Francisco found that Monsanto’s glyphosate-based herbicide Roundup was a substantial factor in causing the cancer of a California man.

The Guardian reports that Edwin Hardeman of Santa Rosa was the first person to challenge Monsanto’s Roundup in a federal trial and alleged that his exposure to Roundup caused him to develop non-Hodgkin’s lymphoma (NHL). Hardeman testified that he had sprayed the herbicide for nearly three decades and that he had gotten it on his skin once.

The Guardian further reported that this case is considered a “bellwether” trial for the hundreds of other plaintiffs in the US with similar claims—the verdict, that is, could affect future litigation in the more than 9,000 similar lawsuits Bayer and Monsanto are facing across the US. That number is conservative:Reutersestimates 11,200 lawsuits are pending.

Reuters reported that the jury’s decision was unanimous—but it wasnota finding of Bayer’s liability for the cancer. That’s the second phase of the trial, which begins on Wednesday, to be handled by the same jury.

The Guardiannoted that the first phase was so strictly limited that judge Vince Chhabria sanctioned Hardeman’s lawyer for referring to internal Monsanto documents in her opening remarks, but that judge Chhabria also said in a procedural order last week: “Although the evidence that Roundup causes cancer is quite equivocal, there is strong evidence from which a jury could conclude that Monsanto does not particularly care whether its product is in fact giving people cancer, focusing instead on manipulating public opinion and undermining anyone who raises genuine and legitimate concerns about the issue.”

The Wall Street Journal (WSJ) reported that Bayer shares dropped more than 12% after the verdict, which showed that Bayer’s acquisition of Monsanto has become its biggest liability. WSJ added that this verdict hits hard: “Bayer had been pointing to this trial as offering a better frame for its argument that scientific evidence proved Roundup was safe, in part because the plaintiff presented other health issues that Bayer argued could have triggered the cancer.”

The Guardian quoted a statement by Bayer spokesman Dan Childs: “We are disappointed with the jury’s initial decision, but we continue to believe firmly that the science confirms glyphosate-based herbicides do not cause cancer. We are confident the evidence in phase two will show that Monsanto’s conduct has been appropriate and the company should not be liable for Mr. Hardeman’s cancer.”

The Guardianalso quoted Jennifer Moore and Aimee Wagstaff, Hardeman’s attorneys, as saying: “Now we can focus on the evidence that Monsanto has not taken a responsible, objective approach to the safety of Roundup.”