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A lawyer for a man who developed cancer after decades of using Monsanto's Roundup said Wednesday that the company "influenced and manipulated" science surrounding the weedkiller and its active ingredient, through its relationships with regulatory officials and by ghost-writing scientific studies.

Aimee Wagstaff of Wagstaff Andrus focused on Monsanto's ghost-writing efforts and "cozy relationship" with some EPA officials during opening arguments on behalf of Edwin Hardeman, a Northern California man who developed non-Hodgkin lymphoma. Wagstaff's remarks came on the first day of the damages and liability phase of the first bellwether case to go to trial in the massive Roundup multidistrict litigation. A San Francisco jury on Tuesday found that Hardeman had proven that Roundup more likely than not was a substantial factor in his cancer.

Judge Vince Chhabria of the U.S. District Court for the Northern District of California, who is overseeing the federal Roundup litigation, split the trial to first consider whether scientific evidence supported the plaintiff's allegations that Roundup causes cancer. Chhabria told jurors Monday morning that they will now consider whether Monsanto is liable for Hardeman's injury, and, if so, what damages the company owes him.

Wagstaff reminded jurors that evidence showed that Hardeman had used 6,000 gallons of Roundup to fend off weeds and poison oak on his Northern California property before his 2015 cancer diagnosis.

"We’re here today now in phase two to talk about Mr. Hardeman and the fact that Mr. Hardeman got cancer from Monsanto’s product," Wagstaff said.

The parties have stipulated that about $200,000 in economic damages are at stake in phase two for Hardeman's medical bills, but plaintiffs are also seeking punitive damages. Wagstaff told jurors Wednesday that they could take into account that Monsanto sold to Bayer AG for $63 billion last year and had a net worth of $7.8 billion and $2.4 billion in cash on hand at the time of the sale.

Monsanto's lead lawyer, Brian Stekloff of Wilkinson Walsh + Eskovitz, said that plaintiffs were trying to take "cherry-picked" evidence, including internal company emails, to make their case.

"We heard pieces of evidence, pieces of stories to try to convince you that Monsanto hid the truth or denied the truth or did something wrong," Stekloff said. Stekloff said that no health organization or regulator had said that Roundup or its active ingredient glyphosate caused cancer during the time that Hardeman was using the product.

"No one said that, based on all the science," he said.

But late in his opening argument for phase two, Stekloff gave an indication of the uphill fight his client is facing at this point in the proceedings.

"This is not a popularity contest," he said. "In the end, we’re not going to ask, 'Do you like Monsanto?'"