WASHINGTON, D.C. --- Representative Henry A. Waxman (D- Beverly Hills, Calif.) issued a subpoena Friday directing the EPA to turn over documents related to its decision to deny California permission to implement its own vehicle emissions laws, the Los Angeles Times reported.

Waxman is chairman of the House Oversight and Government Reform Committee. The subpoena orders the Environmental Protection Agency to provide uncensored copies of its staff recommendation for agency Administrator Stephen L. Johnson.

Johnson ultimately rejected California's request to impose tailpipe emission standards that are stricter than the federal government's.

Senator Barbara Boxer (D-Calif.), who heads the Senate Environment and Public Works Committee, has also requested such records along with EPA correspondence with the White House.

Both Boxer and Waxman are investigating whether Johnson acted against the recommendations of his legal and scientific staff.

Johnson has said he denied California permission to enact its own standards because he believed newly passed federal fuel-economy legislation would reduce emissions and provided a national approach instead of a "patchwork of state rules."