Court Ruling: EPA Failed to Assess Enlist Duo’s Impact on Monarch Butterflies

Judges Send Federal Agency Back to the Drawing Board to Reassess Risk

WASHINGTON, DC – In a victory for NRDC (Natural Resources Defense Council), the U.S. Court of Appeals for the Ninth Circuit today decided the Environmental Protection Agency (EPA) failed to consider harm to monarch butterflies from the destruction of milkweed in agricultural fields in registering the herbicide Enlist Duo for widespread use. The court ordered EPA to address this risk but has allowed Enlist Duo to remain on the market in the meantime. 

The following is a statement from Margaret Hsieh, Senior Attorney at NRDC. 

“This is a win for monarch butterflies whose populations have seen a dramatic decline, in large part due to impacts of pesticides like Enlist Duo. While we are disappointed that Enlist Duo will remain on the market for now, we expect EPA to move quickly in addressing the herbicide’s risks to this imperiled pollinator, so the court can promptly rule on EPA’s new decision.”

More Information: 
NRDC v. E. Scott Pruitt, et al. (Enlist Duo)
Monarch Butterfly Numbers Fall Again


The Natural Resources Defense Council (NRDC) is an international nonprofit environmental organization with more than 3 million members and online activists. Since 1970, our lawyers, scientists, and other environmental specialists have worked to protect the world's natural resources, public health, and the environment. NRDC has offices in New York City; Washington, D.C.; Los Angeles; San Francisco; Chicago; Bozeman, Montana; and Beijing. Visit us at and follow us on Twitter @NRDC

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