WHAT IF THE FACTS WERE DIFFERENT? Suppose that the EPA had carried out scientific tests that showed mercury was relatively harmless as a by-product of electricity generation. How might this have affected the court’s ruling?

THE GLOBAL DIMENSION Because air pollution knows no borders, how did this ruling affect our neighboring countries?

The Environmental Protection Agency (EPA) published a rule—the Delisting Rule—that had the effect of removing from its regulation the emissions of mercury from steam-generating electricity plants that used coal or oil as their energy sources. This Delisting Rule ran counter to the EPA’s own conclusions at the end of 2000 that it was “appropriate and necessary” to regulate mercury emissions. At that time, the agency placed mercury on its list of hazardous air pollutants (HAPs) to be monitored at electricity-generating sites. Later, however, the EPA tried to “delist” mercury from the HAPs list. New Jersey and fourteen other states, plus various state agencies, challenged the EPA’s delisting action.