SACRAMENTO - Invoking executive privilege, the Environmental Protection Agency on Friday refused to provide lawmakers with a full explanation of why it rejected California's greenhouse gas regulations. The EPA informed Sen. Barbara Boxer, D-Calif., that many of the documents she had requested contained internal deliberations or attorney-client communications that would not be shared now with Congress. "EPA is concerned about the chilling effect that would occur if agency employees believed their frank and honest opinions and analysis expressed as part of assessing California's waiver request were to be disclosed in a broad setting," EPA's associate administrator Christopher P. Bliley wrote....