In December, the D.C. Circuit issued a ruling in North Carolina v. EPA (PDF:26.14KB) that will allow EPA’s Clean Air Interstate Rule (CAIR) to remain in effect, for a while at least. The rule addresses a Clean Air Act requirement that states implement measures to prevent significant contributions to non-attainment areas in downwind states. CAIR was designed primarily to address SOx and NOx emissions from power plants in 28 eastern states. EPA petitioned the court to reinstate CAIR following a July ruling in which the D.C. Circuit vacated the rule, calling it ``fatally flawed.`` The court determined that allowing CAIR to remain in effect until its problems can be addressed ``would at least temporarily preserve the environmental values covered by CAIR.``