ELR Citation: 55 ELR 20038
No(s). 23-60069 (5th Cir. Mar 25, 2025)

The Fifth Circuit granted in part and denied in part states' challenges to EPA's disapprovals of SIPs developed in response to the Agency's 2015 decision calling for SIPs to achieve a new ozone NAAQS. Texas, Louisiana, and Mississippi argued EPA's disapprovals of their SIPs were arbitrary and capricious and violated the CAA because the Agency failed to accept the states' interpretation of the "good neighbor provision"; they sought to have the disapprovals vacated. The court held the CAA charged EPA with independently assessing whether a SIP complies with the good neighbor provision. It concluded Texas and Louisiana failed to show that EPA's findings that their SIPs did not satisfy obligations under the provision were arbitrary, capricious, or contrary to the CAA, but that the disapproval of Mississippi's SIP was arbitrary and capricious because it was based on the state's failure to use modeling that was not available at the time the state submitted the SIP. The court denied Louisiana's and Texas' petitions for review, granted Mississippi's petition, vacated EPA's disapproval of Mississippi's SIP, and remanded to EPA.