Debate focuses on whether scientists failed to consider German studies on the safety of glyphosate.

Monsanto is on the attack.

In its fight to keep its blockbuster weedkiller glyphosate on the European market, the American agrichemical giant has spent the last six months fighting accusations that it suppressed negative findings or even ghostwrote key research about whether the herbicide causes cancer.

Now the company is opening a new front with evidence it says debunks the only appraisal by a major world body to label glyphosate as carcinogenic.

POLITICO analyzed hundreds of previously undisclosed documents from a high-profile court case in San Francisco and conducted interviews with numerous scientific experts to tell the tale of the intense battle between Monsanto and scientists over the controversial finding. Monsanto gave POLITICO exclusive access to the court documents.

The global pesticides powerhouse is questioning the findings of scientists who worked for the World Health Organization’s International Agency for Research on Cancer (IARC). In 2015, the agency made glyphosate one of Europe’s most toxic political issues when it concluded the weedkiller “is probably carcinogenic to humans.”

It was a hammer blow to Missouri-based Monsanto, whose blockbuster product Roundup, a favorite among farmers and gardeners, is based on the herbicide. It also whipped up an intense EU-wide debate over whether farmers should be allowed to continue utilizing a product they have used for more than four decades and that they say is vital to preserve yields of common crops from carrots to barley.

IARC’s findings were later dismissed by two EU bodies — the European Chemicals Agency and the European Food Safety Authority — but remain a significant reference point in the debate surrounding the pesticide’s health risks.