States and industry groups challenging the Obama administration's climate rules outlined their legal arguments in opening briefs filed late Friday with a federal appeals court.

First in three related cases on the rules that are being considered by the U.S. Court of Appeals for the District of Columbia is the legal fight over the "endangerment" finding, in which U.S. EPA concluded that carbon emissions are harmful and therefore could be regulated.

The challengers filed three briefs: One by various states, one mainly by industry groups and one backed by Virginia and Texas that questions why EPA did not reconsider the endangerment rule in light of the "Climategate" controversy.

The states' brief, filed by Texas Attorney General Greg Abbott (R), argues that EPA's decisionmaking process was "arbitrary and capricious" under the Administrative Procedures Act because the agency did not "define or measure" endangerment.

The other petitioners, including the American Petroleum Institute and the U.S. Chamber of Commerce, were joined by Alaska on their brief.

Among other things, their lawyers argue that EPA misinterpreted the structure of the Clean Air Act and the meaning of the Supreme Court's 2007 Massachusetts v. EPA ruling, in which the court said carbon emissions fell within the scope of the act.

EPA's failure to follow the correct process has led to "incomplete and irrational decision-making that fails to achieve demonstrable health and welfare benefits, resulting in regulation for regulation's sake," the brief states.

The third brief, filed by Texas and Virginia and submitted by Virginia Attorney General Kenneth Cuccinelli (R), focuses on the Climategate episode relating to emails recovered from a server at the University of East Anglia's Climatic Research Unit in the United Kingdom.

To climate skeptics, the emails showed that scientists manipulated data, although the allegations have been strongly contested and rejected by the British government (ClimateWire, May 10).

The government and its supporters do not file their reply briefs until August.

David Doniger, the policy director of the Natural Resource Defense Council's Climate Center, said today he was unimpressed with what he has seen from those challenging the rule.

"None of them lay a glove on EPA's endangerment determination," Doniger said.

The other cases involving climate rules have different briefing schedules. Briefing in all the cases is not due to be complete until the end of this year (Greenwire, March 23).

Click here to read the state petitioners' brief.

Click here to read the non-state petitioners/intervenors' brief.

Click here to read the brief filed by Virginia and Texas.