Several groups backing the legal fight against U.S. EPA's climate rules outlined their arguments in legal briefs filed late Friday.

One brief was filed by a group of scientists while another was filed by various legal and business organizations.

Both attack EPA's decisionmaking process in reaching its so-called endangerment finding, the rule that concludes that carbon emissions are harmful and therefore can be regulated under the Clean Air Act (CAA). The case is before the U.S. Circuit Court of Appeals for the District of Columbia.

The scientists' brief attacks the research behind EPA's decision, saying there is no evidence that the global climate is changing in an "unusual or anomalous fashion."

The brief also questions certain climate models, saying they "cannot be trusted" to provide data upon which policy decisions are made.

Among scientists signing on to the brief was prominent climate skeptic Roy Spencer, a principal researcher at the University of Alabama in Huntsville.

The second brief was filed by the Atlantic Legal Foundation, Landmark Legal Foundation, Mountain States Legal Foundation and National Federation of Independent Business's Small Business Legal Center.

Their lawyers argue that EPA improperly circumvented a requirement to assess costs.

Among the costs EPA failed to analyze was the impact on small business, the groups claim.

"The agency should have rigorously assessed whether any reasonably expected benefit outweighed the potentially gargantuan costs of exposing such commonplace substances to CAA regulation," the brief states.

The filing came a week after the challengers, including states and industry groups, filed their opening briefs (Greenwire, May 23).

The litigation over the endangerment finding is one of three linked cases concerning climate rules that the appeals court is considering.

EPA and its supporters will file their response briefs in August.

Click here to read the scientists' brief.

Click here to read the small business brief.