A federal court on Friday delivered a mixed decision on an Obama-era rule that called on three dozen states to update their air pollution control plans, upholding parts of the regulation directing states to eliminate liability shields while striking down others.
Environmental groups have long argued that emissions from power plants, refineries and various other industrial sources can rapidly exceed limits during periods of startup, shutdown or malfunction, known in EPA lingo as “SSM.”
In 2014, a court ruled that states cannot include in their state implementation plans, or SIPs, “affirmative defenses” that shield sources of liability for SSM emissions from federal emissions standards because they violate the Clean Air Act.
The Obama administration in 2015 issued a rule known as the “SSM SIP call” that directed 35 states and the District of Columbia to update their state implementation plans to remove various types of affirmative defenses.
