According Reuters, Monsanto has filed a lawsuit against California’s Office of Environmental Health Hazard Assessment (OEHHA) and its acting director Lauren Zeise , after the agency announced in September its intent to add glyphosate (brand name Roundup) to the state’s list of cancer-causing chemicals. California law requires the state to keep a list of such chemicals in order to inform residents of their risk (Proposition 65). The decision to add glyphosate to this list came after the World Health Organization’s International Agency for Research on Cancer (IARC) classified it as a probable human carcinogen in March of 2015.

According to the study by IARC, published in The Lancet Oncology, various studies have shown that people working with the herbicide appear to have an increased-risk of non-Hodgkins lymphoma, while others such as the Agriculture Health Study which followed thousands of farmers exposed to glyphosate, refutes this. However, animal studies that have linked glyphosate to tumors in rats and mice, as well as “mechanistic evidence” such as DNA damage in human cells from exposure to the herbicide, IARC considers sufficient and compelling enough to classify glyphosate as “probably carcinogenic.”

Monsanto has disputed this assessment and in their suit argues that by listing glyphosate as a carcinogen based on the assessment of IARC, the government is ceding regulatory authority to an “unelected, undemocratic, unaccountable, and foreign body” not subject to any federal of state of oversight. According to the suit, this lack of oversight violates the company’s right to due process under California and U.S. law. In addition, they argue that by having to place on their products “a clear and responsible warning” to consumers, as the listing requires, their reputation is being damaged and their first amendment rights violated.

OEHHA has not issued any comment as it has not yet seen the suit.