On September 10, 2010, the U.S. Department of Justice, on behalf of the Environmental Protection Agency, filed briefs in the U.S. Court of Appeals for the District of Columbia Circuit opposing a motion of various industry groups and members of Congress that sought "coordination"—but not consolidation—of approximately 90 pending cases challenging four recent greenhouse gas rules adopted by the EPA pursuant to the Clean Air Act.

These cases collectively challenge a series of EPA actions that establish a regime for regulating greenhouse gas emissions from certain facilities and motor vehicles under the Clean Air Act: (1) the "Endangerment Finding," where EPA determined that greenhouse gas emissions could cause or contribute to endangerment of public health and welfare (74 Fed. Reg. 66,496 (Dec. 15, 2009)); (2) the "Light Duty Vehicle Rule," or "Tailpipe Rule," where EPA set standards to reduce greenhouse gas emissions from new light-duty motor vehicles (75 Fed. Reg. 25,324 (May 7, 2010)); (3) the "Interpretative Memo," or "Triggering Rule," where EPA concluded that greenhouse gas emissions from stationary sources will become subject to regulation under the Prevention of Significant Deterioration ("PSD") and Title V operating permit programs when the Tailpipe Rule takes effect on January 2, 2011 (75 Fed. Reg. 17,004 (Apr. 2, 2010)); and (4) the "Tailoring Rule," where EPA established a scheme for addressing greenhouse gas emissions in PSD and Title V permits issued to certain new or modified stationary sources (70 Fed. Reg. 31,514 (June 3, 2010)).

The State of Texas, the Commonwealth of Virginia, the U.S. Chamber of Commerce, and several other parties have filed D.C. Circuit challenges to EPA's denial (74 Fed. Reg. 49, 556 (Aug. 13, 2010)) of their petitions to reconsider the Endangerment Finding.

The coordination motion asks the D.C. Circuit to combine all of the greenhouse gas rulemaking challenges into one coordinated proceeding before the same three-judge panel. According to the motion, EPA's four final rules "collectively constitute the most expensive suite of administrative regulations ever promulgated by any agency or scrutinized on judicial review by any court." The motion argues that by spreading its reasoning across four separate rulemakings, EPA has left gaps in its justification and created confusion, and that separate judicial review of EPA's "divided decision-making" would impede effective review, require repetitive and duplicative briefing, and could result in conflicting decisions from different panels of the Court of Appeals.

The federal government opposes the motion on the grounds that there is no logical or legal justification for a "one-size-fits-all global coordination." EPA argues that each rulemaking involves agency actions that are separate and distinct in terms of the statutory provisions that govern the types of sources regulated and the associated administrative records. EPA proposes an alternative three-prong approach to coordinating/consolidating the cases: (1) independent consideration of the previously consolidated cases challenging the "LDV Rule"/"Tailpipe Rule"; (2) coordination or consolidation of cases challenging either the "Endangerment Finding" or EPA's denial of petitions for reconsideration of the "Endangerment Finding"; and (3) consolidation of the cases challenging the "Interpretative Memo" and the "Tailoring Rule."