This February, a federal appeals court tossed out the Clean Air Mercury Rule and its cap-and-trade program and ordered that mercury be regulated more stringently as a hazardous air pollutant. Adding insult to injury, the court made its ruling effective one month later. While the EPA regroups, state energy and environmental regulators will have an opportunity to look closely at recent power plant permits for guidance. This article reviews the technology options and regulatory approach for mercury control used on recently permitted and currently operating coal-fired plants.