A little-noticed order issued by President Bush almost four years ago gives White House lawyers the right to block the release of memos written by Supreme Court nominee John G. Roberts Jr. when he worked for President Reagan.

The order, signed by Bush in November 2001, said the "incumbent president" had the right to approve the release of papers from the presidential libraries of his father, George H.W. Bush, and Ronald Reagan.

It set off a furor at the time among historians, archivists and librarians. They said it all but repealed the Presidential Records Act, a 1978 law that decreed a president's records were public property, not the private property of the former president. Under this law, a former president's papers were to be opened to the public 12 years after he left office. Exceptions could be made for national security reasons.

Bush's executive order added a new check. It said the "incumbent president may assert any constitutionally based privilege" after the 12 years had lapsed to block the release of files. Included among these many privileges were "records that reflect ... legal advice or legal work."