Monsanto Co. and officials within the Environmental Protection Agency are fighting legal efforts aimed at exploring Monsanto’s influence over regulatory assessments of the key chemical in the company’s Roundup herbicide, new federal court filings show.

The revelations are contained in a series of filings made within the last few days in the U.S. District Court for the Northern District of California as part of litigation brought by more than 50 people suing Monsanto. The plaintiffs claim they or their loved ones developed non-Hodgkin lymphoma (NHL) after exposure to Roundup herbicide, and that Monsanto has spent decades covering up cancer risks linked to the chemical.

Lawyers for the plaintiffs want the court to lift a seal on documents that detail Monsanto’s interactions with former top EPA brass Jess Rowland regarding the EPA’s safety assessment of glyphosate, which is the key ingredient in Roundup. Monsanto turned the documents over in discovery but marked them “confidential,” a designation plaintiffs’ attorneys say is improper. They also want to depose Rowland. But Monsanto and the EPA object to the requests, court documents show.