(Adds details from court hearing, comments by Bayer and plaintiff lawyer)
SAN FRANCISCO, Oct 10 (Reuters) - Bayer AG's Monsanto unit on Wednesday received a tentative ruling for a new trial on the $250 million in punitive damages awarded by a jury to a groundskeeper who alleged the company's glyphosate-based weed killers, including Roundup, caused his cancer.
According to a court filing in San Francisco's Superior Court of California, Judge Suzanne Bolanos was considering whether to grant the company's motion for a new trial on the punitive damages.
The judge's ruling, granting a new trial on the punitive damages, is tentative and was being discussed at a court hearing on Wednesday.
Bolanos at the close of the two-hour hearing in front of a packed courtroom said the parties had until Friday to submit their proposed orders in response to her ruling.
California judges often issue tentative rulings, which are then finalized after a hearing with few major changes.
The Aug. 10 award to Dewayne Johnson included $39 million in compensatory damages. Johnson, whose doctors say he is likely to die within the next two years, attended Wednesday's hearing.
The combined $289 million verdict marked the first decision finding that Monsanto had failed to warn consumers of the alleged cancer risks posed by glyphosate, the world's most widely used weed-killer.
Bayer, which bought Monsanto earlier this year for $63 billion, faces more than 8,000 similar lawsuits in the United States.
The German company has denied the allegation and has said that decades of real-world application and scientific studies have shown the chemical to be safe for human use.
Investors have raised concerns over the litigation risk, with Bayer shares falling sharply after the original decision and still trading some 20 percent below their pre-verdict level at 75 euros ($86.53) on Wednesday.
In September 2017, the U.S. Environmental Protection Agency concluded a decades-long assessment of glyphosate risks and found that the chemical was not a likely carcinogen to humans. However, in 2015 the cancer unit of the World Health Organization classified glyphosate as "probably carcinogenic to humans."
On Wednesday, the judge said that Johnson had failed to meet his burden of producing clear and convincing evidence of malice or oppression by Monsanto, a requirement for allowing a jury to award punitive damages.
Bayer in a statement on Wednesday said it agreed with Bolanos' tentative ruling.
"The company continues to believe that the evidence at trial does not support the verdict and the damage awards," Bayer said.
But Michael Miller, a lawyer for Johnson, disagreed.
"We have a jury that got it right," Miller told the court, adding that the jury had reached a unanimous verdict after careful deliberations, supported by sufficient science.
Monsanto had asked Bolanos in court filings on Sept. 18 to set aside the entire verdict or, in the alternative, reduce the award or grant a new trial. The judge is still considering all of the company's motions.
Bolanos throughout the hearing directed sharp questions at Johnson's lawyers, singling out remarks they made to the jury during trial. Monsanto lawyers said a comment over company executives "popping champagne bottles" if Johnson loses the trial were prejudicial and aimed at inciting jurors.
Johnson's case, filed in 2016, was fast-tracked for trial due to the severity of his non-Hodgkin's lymphoma, a cancer of the lymph system, that he alleged was caused by years of exposure to Roundup and Ranger Pro, another Monsanto herbicide that contains glyphosate. ($1 = 0.8668 euros) (Reporting by Jim Christie in San Francisco Writing and additional reporting by Tina Bellon in New York; Editing by Bill Berkrot)