A district court ordered EPA to issue federal implementation plans fully resolving interstate transport obligations under the CAA's "good neighbor" provision for the 2008 ozone NAAQS. EPA conceded…

The D.C. Circuit held that EPA unlawfully revoked the 1997 ozone NAAQS when it implemented the 2008 standard. In 2008, EPA set the ozone NAAQS at 75 parts per billion (ppb). In 2015, when…

The D.C. Circuit upheld EPA's compliance deadlines for states to meet the NAAQS for fine particulate matter (PM2.5). The court previously had ruled that the framework EPA had been applying to PM2.…

A district court ordered EPA to impose a "good neighbor” federal implementation plan (FIP) for Texas with respect to the 1997 fine particulate matter (PM2.5) NAAQS. In 2015, the D.C. Circuit…

A district court dismissed environmental groups' CAA citizen suit against EPA for failing to respond to their 2011 petition concerning ammonia gas pollution. In 2011, the groups petitioned EPA…

The D.C. Circuit, on remand from the U.S. Supreme Court, invalidated EPA's 2014…

The D.C. Circuit denied petitions for review of EPA decisions regarding nonattainment designations under the 2008 ozone NAAQS. Several states, counties, industrial entities, and environmental…

The D.C. Circuit denied petitions for review challenging EPA's disapproval of a revision to Kansas' proposed SIP revision for the 2006 fine particulate matter (PM2.5) NAAQS. EPA disapproved the…

An Arizona court overturned the state's issuance of an air permit for a proposed open-pit copper mine. An environmental group argued that the state's approval of the permit was arbitrary and…

The D.C. Circuit held that EPA's regulations implementing the 2008 NAAQS for ozone exceed the Agency’s authority under the CAA. In 2008, EPA revised and strengthened the standards for ozone…