Lee Johnson, a 46-year-old resident of Vallejo, California developed a severe skin rash in 2014, two years after he started spraying Roundup as part of his groundskeeping job...The rash turned into an aggressive form of non-Hodgkin lymphoma, a cancer of the lymphatic system...His is one of 2,400 lawsuits filed against Monsanto by cancer victims in courts across the country, and Johnson’s case is the first one scheduled for a jury trial.  These victims are suing to hold Monsanto accountable, claiming that glyphosate, the listed, active ingredient in its popular herbicide Roundup, caused their non-Hodgkin lymphoma...The lawsuits raise the question of whether the courts can accomplish what U.S. regulators have not: control or accountability over glyphosate, a chemical that international authorities in the U.N.’s top cancer group have deemed a probable carcinogen...U.S. District Judge Vince Chhabria began the process of determining whether or not scientific experts in these trials are using sound methods to reach their conclusions, and which experts can be called to the stand during upcoming federal trials...The 2,000 cases pending in state courts are not subject to Chhabria’s gatekeeping decisions and are already proceeding with the first case—Johnson’s—which is scheduled to begin in June...The hearings marked the first time that Monsanto scientists faced off in court against three top scientists who had served on the U.N.’s International Agency for Research on Cancer (IARC), which in 2015 labeled glyphosate as a probable carcinogen...Monsanto’s experts...challenged the validity of the plaintiffs’ experts’ data and studies and presented their own views of the data as well as conflicting research...