A conservative public policy think tank filed suit on Tuesday in U.S. District Court in Washington, D.C., seeking some 7,300 emails from the Treasury Department that it failed to obtain through the Freedom of Information Act.

In its FOIA, the Competitive Enterprise Institute requested emails that included the word “carbon” from the agency that would be charged with setting up cap-and-trade or a carbon tax.

“The emails, between Treasury officials, lawmakers, left-wing pressure groups, contributors and other special interest groups, reflect efforts by the Treasury to build a coordinated support for a carbon tax,” a press release issued by CEI on Tuesday stated.

“The administration has refused to release the emails of discussions claiming that it would be expensive to photocopy all 7,000 emails and because the emails ‘would not significantly inform the public about operations or activities of government,’” CEI said.