(Reuters) — A federal judge overseeing lawsuits alleging Bayer AG’s glyphosate-based Roundup weed killer causes cancer on Friday declined to reconsider a ruling that limits evidence the plaintiffs in the litigation consider crucial to their cases.

U.S. District Judge Vince Chhabria during a hearing in San Francisco federal court denied a plaintiff lawyer’s request to review the decision, saying trials before him should focus on scientific evidence.

Judge Chhabria on Thursday granted Bayer unit Monsanto’s request to split an upcoming trial into two phases. The order initially bars lawyers for plaintiff Edwin Hardeman from introducing evidence that the company allegedly attempted to influence regulators and manipulate public opinion.

The decision lifted Bayer’s shares, which on Friday closed up 6.7% at €64.90 ($74.02).

Thursday’s order applies to Mr. Hardeman’s case, which is scheduled to go to trial on Feb. 25, and two other so-called bellwether trials intended to help determine the range of damages and define settlement options for the rest of the 620 Roundup cases before Judge Chhabria.

Brent Wisner, a lawyer for the plaintiffs, during Friday’s hearing told Judge Chhabria his ruling is “unfair” as their scientific evidence allegedly showing glyphosate causes cancer is inextricably linked to Monsanto’s alleged wrongful conduct.

“The science doesn’t exist in some isolated, untouched world,” Mr. Wisner said, adding that evidence of Monsanto’s alleged attempts to manipulate, misrepresent and intimidate scientists has to be included.

The lawyers contend that such evidence, including internal Monsanto documents, showed the company’s misconduct and were critical to a California state court jury’s August 2018 decision to award $289 million in a similar case. The verdict sent Bayer shares tumbling at the time, though the award was later reduced to $78 million and is under appeal.

But Judge Chhabria slammed that request, saying he did not want plaintiffs to “focus on misrepresenting statements” by Monsanto employees.

“My point is you’re mischaracterizing what Monsanto people have said, you’re putting your own spin on (it),” Judge Chhabria said.

Bayer denies that glyphosate causes cancer, saying decades of independent studies have shown the world’s most widely used weed killer to be safe for human use.

But the company faces more than 9,300 U.S. lawsuits over Roundup’s safety in state and federal courts across the country.

Under Judge Chhabria’s order, evidence of Monsanto’s alleged misconduct would be allowed only if glyphosate was found to have caused Hardeman’s cancer and the trial proceeded to a second phase to determine Bayer’s liability.