Dist. Ct. erred in directing defendant-Dept. of Justice to turn over 440 internal memorandums and emails from legal staff representing EPA and Corps of Engineers generated during CERCLA lawsuit seeking environmental cleanup costs from plaintiffs and other entities after plaintiff sought said documents pursuant to FOIA, and after Dist. Ct. rejected defendant’s claim that said documents/emails were protected by attorney work product privilege. Although plaintiff sought said documents to determine whether said federal agencies colluded so as to understate any contribution by said agencies to pollution of Superfund site, work product privilege applied where U.S., as opposed to said agencies, was real party in CERCLA action, and information in nature of attorney work product exchanged among Dep’t.’s lawyers is not information exchanged among adverse parties, and thus was privileged from disclosure to plaintiff.