A federal appeals court on Thursday overturned the U.S. Environmental Protection Agency's (EPA) approval of a controversial pesticide, saying the agency violated federal law by giving a green light without obtaining or reviewing reliable studies on the neonicotinoid's impact on honeybees.

The Ninth Circuit Court of Appeal's ruling (pdf) in the case, which was brought by environmental law firm Earthjustice, means that the pesticide in question—a neonicotinoid known as sulfoxaflor—may not be used in the U.S. unless the EPA re-approves it after obtaining the necessary analysis of its effects on pollinators.

Other neonicotinoids, such as clothianidin, imidacloprid, and thiamethoxam, have been linked to population declines among honeybees, bumblebees, and other insects, which environmental activists say threatens food security.

"Our country is facing widespread bee colony collapse, and scientists are pointing to pesticides like sulfoxaflar as the cause," Greg Loarie, Earthjustice's lead counsel in the case, said Thursday. "The Court's decision to overturn approval of this bee-killing pesticide is incredible news for bees, beekeepers, and all of us who enjoy the healthy fruits, nuts, and vegetables that rely on bees for pollination."

Earthjustice brought the case on behalf of the environmental nonprofits Center for Food Safety, the Pesticide Action Network, and Beyond Pesticides. It also represented a coalition of groups including the Pollinator Stewardship Council and National Honeybee Advisory Board, among others.

Michele Colopy, program director of the Pollinator Stewardship Council, said on Thursday that the EPA's "decision process to unconditionally register Sulfoxaflor was based on flawed and limited data.... We can protect crops from pests and protect honey bees and native pollinators."

"To do this EPA's pesticide application and review process must receive substantial scientific evidence as to the benefits of a pesticide, as well as the protection of the environment, especially the protection of pollinators," Colopy said.