The U.S. Environmental Protection Agency (EPA) failed to follow established guidelines for determining cancer risk, ignored important studies, and discounted expert advice from a scientific advisory panel in officially declaring that the weed killer glyphosate was “not likely to be carcinogenic,” a federal court said in an order issued Friday.

The 9th U.S Circuit Court of Appeals said the agency’s 2020 assessment of glyphosate, the active ingredient in Roundup, was flawed in many ways, applying “inconsistent reasoning” in finding that the chemical does not pose “any reasonable risk to man or the environment.”

The court vacated the human health portion of the EPA’s glyphosate assessment and said the agency needed to apply “further consideration” to evidence. The 9th Circuit also said that the EPA was in violation of the Endangered Species Act in its assessment of glyphosate.

The decision comes at a critical time for Monsanto owner Bayer AG. Bayer is seeking to put an end to thousands of lawsuits filed by U.S. Roundup users who developed non-Hodgkin lymphoma and allege their exposure to the weed killer is to blame for their cancers.