What is the Bush Administration hiding?

Vice President Dick Cheney must preserve a broad range of records from his time in office, a federal judge ordered Saturday, ruling in favor of a private watchdog group.
U.S. District Judge Colleen Kollar-Kotelly found that the records are not excluded from preservation under Presidential Records Act, which gives the national archivist responsibility over the custody of and access to the records at the end of a president's final term.

The Bush administration had sought a narrow interpretation of the act to allow for fewer materials to be preserved by the National Archives.

my obvious question is why?  what are they hiding?