The D.C. Circuit vacated an interim final rule issued by EPA that would allow manufacturers of heavy-duty diesel engines to pay nonconformance penalties in exchange for the right to sell engines that fail to satisfy nitrogen oxide requirements. In 2001, EPA issued a rule requiring a 95% reduction in...

The Sixth Circuit held that the CAA's citizen suit provision does not allow an environmental group to file suit to compel the state of Ohio to administer a particular federal CAA regulation it has chosen no longer to administer. In 2006, the Ohio General Assembly passed legislation that allows the s...