A document leaked from the EPA offers an inside look on the Agency’s plans with respect to making an “endangerment finding” as a prelude to regulating GHGs under the Clean Air Act (“CAA”). In its April 2007 decision Massachusetts v. EPA, the U.S. Supreme Court ordered EPA to determine either that GHGs do endanger public health and/or welfare, or that they do not. According to the internal document, a proposed determination that global warming does pose a threat to both public health and welfare is expected to be issued by EPA Administrator Lisa Jackson on April 16th. Public comment will be then accepted for a sixty day period.

The endangerment finding is not expected to include specific regulations aimed at controlling GHG emissions. The Agency does not appear to have a timeline for the development of such regulations, but the endangerment finding is a necessary first step in that process. A key issue is whether EPA should find that GHGs endanger public health, public welfare, or both. According to the leaked document, it appears that EPA intends to determine that both public health and welfare are endangered. If EPA does in fact finalize a finding that global warming poses such a threat, then EPA will be legally obligated to regulate GHG emissions under the Clean Air Act, and extensive regulatory efforts will follow. As these developments at the Agency level unfold, Congress continues to struggle with proposed legislation that would directly govern GHG emissions and potentially preempt regulation of GHG emissions by EPA under the authority of the CAA.