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…

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…

The D.C. Circuit, on remand from the U.S. Supreme Court, invalidated EPA's 2014 emissions budgets under the transport rule, also known as the Cross-State Air Pollution Rule, as applied to…

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…

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…

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…

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…

The D.C. Circuit denied industry groups' petition for review challenging EPA's 2013 primary NAAQS for fine particulate matter. In the final rule, EPA lowered the level of the particulate…