In Roundup Case, the Science Will Go on Trial First

In a San Francisco courtroom this month, a jury will be asked to weigh a complicated question: Did Roundup weedkiller cause a man’s cancer?

The jurors will assess the credibility of competing studies that delve into cell mutations, cancer epidemiology and genotoxicity. They’ll hear evidence purporting to show why California resident Edwin Hardeman’s exposure to Roundup was dangerous, and other analyses arguing it was perfectly safe.

But unlike in a prior trial brought against the herbicide’s maker, Bayer AG, the jurors won’t simultaneously hear allegations that the company hid dangers about its product from the public. Instead, they’ll take part in an unusual split trial focused first on the science, and then, only if they find the plaintiff’s claims valid, on the question of negligence.

A federal judge approved a request by the company for this slimmed-down trial, over the objection of the plaintiff’s lawyers, to let the jury evaluate the alleged dangers of Roundup without what he called the significant distraction of attacks on the company’s behavior.

The approach is the latest attempt by courts to resolve a long-running debate over how to ensure the fairest decisions in cases concerning complicated science. The results could influence hundreds of similar Roundup cases—and guide judges in other cases that hinge on science.

In Roundup Case, the Science Will Go on Trial First

Courts have grappled for decades to find the right balance of what scientific evidence jurors can see. On one hand, the threshold for admissible scientific evidence needs to be low enough to encourage consumers to bring legitimate grievances against makers of potentially harmful products. On the other hand, it needs to be high enough to prevent floods of frivolous lawsuits based on faulty science or bogus claims.

Judges have typically played a central role in the debate by screening expert witnesses at the outset of trial. But the level of expertise of the judges themselves varies, as does the leeway afforded them to decide what gets in or not.

At the federal level, judges follow a uniform standard for how to allow in expert witnesses and scientific evidence. States, however, have diverged in their approaches. New Jersey last year tightened expert-witness standards to help block what corporate defendants often deem “junk science.” Florida’s highest court, meanwhile, in October reversed a legislative proposal that would have aligned the state with the generally more stringent federal threshold.

Further complicating the issue: Science is often unsettled within the medical community, and the root causes of a disease are often unknown.

“If the science is not junk, but at a stage of knowledge that’s truly indeterminate, what do we do about that?” said Alexander Lemann, a professor at Marquette University Law School. “It’s a problem that’s not solved by having the judge be a more aggressive gatekeeper.”


  • 1974: Environmental Protection Agency first registers glyphosate, the primary chemical in Roundup, for use in the U.S. as Monsanto brings the product to market.
  • 2015: International Agency for Research on Cancer, a World Health Organization unit, deems glyphosate as probably carcinogenic to humans.
  • 2016: Bayer makes a play for Monsanto as the company faces a few hundred cases alleging harms from Roundup.
  • 2017: EPA most recently reaffirms glyphosate is “not likely to be carcinogenic to humans.”
  • June 2018: Bayer closes its acquisition of Monsanto.
  • August 2018: San Francisco jury awards former groundskeeper $289.2 million in first Roundup trial.
  • October 2018: Judge reduces trial award to $78.5 million, maintains finding that Monsanto acted with malice. Decision is on appeal.

In the Roundup case, around 9,300 home gardeners, landscapers and agricultural workers have sued Bayer in the U.S., claiming the weedkiller causes non-Hodgkin lymphoma and other cancers. Bayer inherited the potential liability through its acquisition last summer of seed and pesticide maker Monsanto Co.

The U.S. Environmental Protection Agency has said for decades that glyphosate, the primary chemical in Roundup, is not likely to be carcinogenic to humans. In 2015, the International Agency for Research on Cancer, a World Health Organization branch, designated glyphosate as “probably carcinogenic to humans.” That kicked off a wave of litigation and regulatory scrutiny around the world.



Leave a Reply

Please log in using one of these methods to post your comment: Logo

You are commenting using your account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s