U.S. District Judge Vince Chhabria, Northern District of California

SAN FRANCISCO — Monsanto Co. has lost out on an early bid to knock out more than 400 federal cases claiming that the active ingredient in its Roundup herbicide causes a type of cancer.

In what he called “a very close question,” U.S. District Judge Vince Chhabria of the Northern District of California, who is overseeing the cases, declined to grant Monsanto’s motion for summary judgment that plaintiffs couldn’t prove that the glyphosate in Roundup causes non-Hodgkin lymphoma (NHL), a type of cancer affecting white blood cells. Although Chhabria wrote that evidence plaintiffs put forward “seems too equivocal to support any firm conclusion that glyphosate causes NHL,” he found that they could put on admissible evidence that could convince a reasonable jury to conclude otherwise.

The ruling comes after Chhabria bifurcated the multidistrict litigation to create a “general causation” phase to deal with the basic question of whether plaintiffs could credibly show that glyphosate could cause cancer in humans at realistic exposure rates. Chhabria held that the opinions of three expert witnesses that plaintiffs put forward to prove causation were “shaky” but “admissible.” The ruling allows the plaintiffs to move on to the next phase of the cases where they must prove that glyphosate caused a particular, individual case of NHL.

“Given how close the question is at the general causation phase, the plaintiffs appear to face a daunting challenge at the next phase,” Chhabria wrote. “But it is a challenge they are entitled to undertake.”

In an emailed statement, Monsanto Vice President Scott Partridge pointed out that Chhabria’s order barred testimony from two of the plaintiffs’ expert witnesses and “severely limited” testimony from another.

“Moving forward, we will continue to defend these lawsuits with robust evidence that proves there is absolutely no connection between glyphosate and cancer,” Partridge said. “We have sympathy for anyone suffering from cancer, but the science clearly shows that glyphosate was not the cause.”

Chhabria’s decision comes just a day after trial got underway in San Francisco Superior Court in a case brought by Dewayne “Lee” Johnson, a former groundskeeper diagnosed with non-Hodgkin lymphoma four years ago who claims exposure to Roundup caused his illness. Johnson’s case is one of about 150 cases that are being coordinated in the California state courts and the first of about 4,000 filed against Monsanto nationwide to go to trial.

The company is represented by defense counsel at Hollingsworth LLP in Washington, D.C. in the federal MDL.

Aimee Wagstaff of Andrus Wagstaff in Denver, one of the lead counsel for plaintiffs in the case, said that she was pleased with the order and “ready to move this case to trial.”

“I’m pleased my clients will have their day in court,” she said.