Essentially putting global warming science on trial, Texas officials on Thursday expanded their arguments in a lawsuit meant to prevent the federal regulation of greenhouse gases.

In motions submitted Thursday to the U.S. Court of Appeals for the D.C. Circuit, Texas Attorney General Greg Abbott accused the federal Environmental Protection Agency of relying on faulty science for its proposals to regulate greenhouse gases.

The briefs build on a federal suit filed in February by Texas and other states against the EPA, which in December issued an endangerment finding that carbon dioxide emissions threaten the public health and welfare of current and future generations.

The endangerment finding, which opens the way to further regulations, spun out of a 2007 U.S. Supreme Court ruling that the EPA had the authority to regulate greenhouse gases.

The EPA said its scientific conclusions were based on work by three groups: the U.S. Global Climate Research Program, the United Nations' Intergovernmental Panel on Climate Change and the National Research Council, which synthesize thousands of studies to convey a consensus on what scientific literature shows about climate, according to the agency.

In February, Abbott, who is seeking re-election this year, said that in relying on the U.N. panel's data, the EPA "outsourced the scientific basis for its greenhouse gas regulation to a scandal-plagued international organization that cannot be considered objective or trustworthy."

The American-Statesman's PolitiFact Texas team deemed "Barely True" Abbott's statement, which drew attention to claims that scientists for the U.N. panel from at least two universities had suppressed data that could undermine global warming work.

Since the February claim, independent reviews of work by climate scientists at East Anglia University in England and Penn State University found no evidence that they had actively suppressed or falsified data.

"By delegating its judgment on climate science to the (U.N. group) and others, EPA exposed its conclusions to the errors and biases of unaccountable volunteer scientists, and undermined the validity of the endangerment finding," reads a brief filed by the Texas attorney general's office.

The state is challenging proposals to limit emissions of greenhouse gases from light-duty-vehicle tailpipes and large industrial facilities.

Abbott and Gov. Rick Perry have said greenhouse gas rules could cripple the Texas economy.