On June 25, 2019, US EPA issued a proposed rule that would
reverse the "once in, always in" policy for sources of
hazardous air pollutants (HAP) that has been in place for more
than 20 years. The rulemaking formalizes a January 2018 US
EPA memorandum repealing the
policy, an action that was challenged by environmental
groups and is currently before the D.C. Circuit Court of Appeals.
The petitioners claim that the memorandum conflicts with the
structure and purpose of Section 112 of the Clean Air Act (CAA).
The court heard oral arguments on April 1, 2019, but has not yet
ruled. To the extent that petitioners claim the memorandum should
have been subject to notice and comment, US EPA's proposed rule
may answer that challenge. However, the petition raises substantive
issues related to whether the policy repeal is consistent with the
CAA and the court's ruling on these issues will likely affect
the outcome of this rulemaking.
