Editors' Summary: David P. Novello surveys the significant developments in hazardous air pollutant (HAP) regulation in this Article. Since early 2007, EPA has suffered significant reversals in the U.S. Court of Appeals for the District of Columbia (D.C.) Circuit concerning its HAP regulatory program, including the remand of three national emission standards for hazardous air pollutants. In early 2008, the D.C. Circuit also ruled invalid EPA's decision on how to regulate mercury emissions from electric utilities. In light of these recent reversals, the Agency is reworking standards still in development and needs to go back to the drawing board to redevelop maximum available control technology standards for electric utilities. Courts have also ordered the Agency to promulgate a number of "area source" standards by the middle of next year, and EPA has been busy making "residual risk" determinations. This Article describes these cases and controversies surrounding developments in EPA's air toxics program during the eventful past 18 months.