Jump to Navigation
Jump to Content

Center for Biological Diversity v. Environmental Protection Agency

ELR Citation: 44 ELR 20119
Nos. 12-1238, (D.C. Cir., 05/27/2014)

The D.C. Circuit upheld EPA’s decision to defer adopting new secondary NAAQS for oxides of sulfur (SOx) and nitrogen (NOx) pending further scientific study. Citing doubts about the accuracy of its aquatic acidification index model—used to quantify the connection between SOx and NOx in the air and the expected harm from acid rain in any particular region—EPA decided not to promulgate a new, combined SOx-NOx secondary standard. Instead, EPA decided to gather additional data and retain the existing individual nitrogen dioxide and sulfur dioxide standards. Environmental groups disputed EPA’s conclusion that it lacked sufficient scientific information to make a reasoned judgment. But EPA explained at length that the uncertainty it faced was unusually profound; specifically, data gaps in the Agency's aquatic acidification index model were "of such a significant nature and degree" that any rule promulgated would not have been based on “reasoned judgment.” In light of the deference due EPA’s scientific judgment, and because the CAA requires a reasoned judgment that EPA could not form here, EPA did not violate the CAA. The court, therefore, denied the groups' petitions for review.