Monsanto is facing its first federal trial over allegations that its Roundup weedkiller causes cancer, but a U.S. judge has reportedly blocked attorneys from discussing the corporation’s alleged manipulation of science.

The Guardian reported that in an extraordinary move in a packed San Francisco courtroom on Monday, U.S. judge Vince Chhabria threatened to sanction and “shut down” a cancer patient’s attorney for violating his ban on talking about Monsanto’s influence on government regulators and cancer research.

“You’ve completely disregarded the limitations that were set upon you,” the visibly angry judge was quoted as saying to attorney Aimee Wagstaff, threatening to prevent her from continuing. “If you cross the line one more time … your opening statement will be over … If I see a single inappropriate thing on those slides, I’m shutting you down.”

In a blow to the plaintiffs, Chhabria this year approved Monsanto’s request to prohibit Hardeman’s attorneys from raising allegations about the corporation’s conduct, saying issues about its influence on science and government were a “significant … distraction”.

That means jurors must narrowly consider the studies surrounding Roundup’s cancer risks, and if they rule that Monsanto caused Hardeman’s illness, then in a second phase the jury would learn about the company’s conduct when assessing liability and punitive damages, The Guardian reported.

Hardeman’s trial is considered a “bellwether” case for hundreds of other federal plaintiffs who have made similar claims, meaning its outcome could have an impact on the course of future litigation and potential settlements. The high-stakes case comes amid growing global scrutiny of the health impacts of glyphosate, which is sold under the Roundup brand.

Germany-based Bayer purchased U.S.-based Monsanto last year, and its share price was rocked by the US$289 million verdict in California state court that Roundup had caused a man's cancer.

To read the full story, click here.