By way of the Center for Democracy and Technology, and first covered by the San Jose Mercury News, the non-partisan Congressional Research Service recently completed a thorough review of California's request for a federal waiver to enforce its own greenhouse gas controls on auto emissions. The report, which has been circulating on Capitol Hill but was made available publicly by CDT, comes to the conclusion that the EPA's foot-dragging in this matter is likely for naught, as the state "appears to have a strong case."
Of particular significance: CRS analyst James E. McCarthy notes repeatedly that the Supreme Court's ruling in Massachusetts v. EPA strengthens the state's case. According to CRS, the Court's ruling adds significant leeway for states to take incremental action against global warming's pernicious effects, and any argument by EPA that the state's request therefore does not meet "compelling and extraordinary" conditions is also undermined by the Court's ruling:
Though not interpreting section 209, the Court plainly took the prospect of climate change quite seriously...Moreover, implied the Court, the fact that reduction in GHGs from California vehicles can be but a small part of the solution is not a reason to discount it: "[a]gencies ... do not generally resolve massive problems in one fell regulatory swoop."50 Thus, Massachusetts v. EPA arguably adds support to a Section 209(b)(1)(B) finding that California needs a GHG emission reduction to meet compelling and extraordinary conditions.
CRS also notes that out of 53 previous formal waiver requests (and 95 total requests), all appear to have been granted either in whole or in part; at least one EPA official recalls that "I don't think we've ever outright denied a request [by California]." Given both that rule-making precedent and the firm support provided by the Supreme Court, we're hoping that they won't make this time the first.
UPDATE [9/5, 11:30 AM]: More over at Gristmill from the always-witty David Roberts.