A federal appeals court yesterday expanded the scope of privileges for presidential communications to include those of senior advisers.

The decision could affect the Clinton administration's legal battle with the Whitewater independent counsel over a White House lawyer's notes of conversations with first lady Hillary Rodham Clinton.

The three-judge panel of the U.S. Court of Appeals for the D.C. Circuit, which issued the ruling, said the expanded presidential communications privilege is "not absolute," however, and can be overcome.

In a 55-page opinion, Judge Patricia M. Wald wrote that the panel was "ever mindful of the dangers involved in cloaking governmental operations in secrecy," and for that reason sought to strike "a delicate and appropriate balance" between the public's right to be informed of executive decisions and a president's right to receive candid advice from aides.

"The very reason that presidential communications deserve special protection . . . is simultaneously the very reason why securing as much public knowledge of presidential actions . . . is of paramount importance," Wald wrote on behalf of herself and Judges Douglas H. Ginsburg and Judith W. Rogers.

"Presidential advisers do not explore alternatives only in conversations with the president or pull their final advice out of thin air. . . . Rather, the most valuable advisers will investigate the factual context of a problem in detail, obtain input from all others with significant expertise in the area, and perform detailed analyses of several different policy options" before making a recommendation to the president, Wald wrote. "If these materials are not protected by the presidential privilege, the president's access to candid and informed advice could well be significantly circumscribed."

Charles F. C. Ruff, President Clinton's White House counsel, hailed the decision, saying it "strongly reaffirmed the president's constitutional right to protect confidential communications both directly with the president and among his senior advisers."

The panel's decision came in a nearly three-year-old legal battle between the White House and independent counsel Donald C. Smaltz over 84 documents withheld by the Clinton administration. The documents were generated during an internal White House investigation of former agriculture secretary Mike Espy's acceptance of gifts from companies he was supposed to be regulating.

Specifically, the three-judge panel reversed a decision by a U.S. District Court judge who had sided with the White House by saying it did not have to turn over the 84 documents despite a grand jury subpoena for them. The panel found fault with Chief U.S. District Judge John Garrett Penn for failing to explain his reasons or conducting an analysis of each document. The appeals court ordered Penn to reexamine the documents and release those that contain "any information that might reasonably be relevant" to Smaltz's investigation, especially if they contain "important evidence" that he cannot obtain elsewhere.

Smaltz will have another opportunity to make his case for obtaining all the 84 documents, knowing now where the appellate court found holes in his argument. Charles G. Bakaly, a spokesman for Smaltz, said the independent counsel is "gratified" by the court's decision, which "among other things, sharpened the definition of presidential privilege."

In the opinion, Wald signaled that Smaltz will get at least some of the documents he wants. But she also picked up where Watergate-era cases left off on the issue of privileged presidential communications. By doing so, she explicitly extended the privilege by giving the president and his advisers more wide-ranging protection than ever before.

In this case, Clinton never personally viewed any of the documents in question. But because he ordered the internal probe to help him determine whether he should fire Espy, a Cabinet member, Wald said the advisers and their underlings need the "sufficient elbow room" that presidential privilege provides to offer candid advice.

"I think she has significantly carried the law forward," said Georgetown University Law Center Professor Paul F. Rothstein. "She does fill in . . . the gaps in a significant way."

Because Ginsburg, a Republican appointed by President Ronald Reagan, signed on to an opinion written by a liberal Democrat like Wald, Rothstein said, the decision could affect the Supreme Court's consideration of White House efforts to keep secret notes involving Hillary Clinton's January 1996 grand jury appearance. The White House has asserted attorney-client privilege as its reason for withholding those notes. The Supreme Court is expected to announce as early as next week whether it will hear the case next term.