WASHINGTON — The Bush administration says the president’s immediate advisers are absolutely immune from having to appear before Congress, but legal scholars say the issue isn’t that clear cut.

The question grew more pressing Wednesday as President Bush ordered a former White House counsel, Harriet Miers, to defy a congressional summons in the controversy over the administration’s dismissals of federal prosecutors.

The Democratic chairmen of the Senate and House judiciary committees have said they would consider introducing contempt of Congress citations against any subpoena recipients who resist.

House Judiciary Committee Chairman John Conyers, Democrat of Michigan, could begin that process as early as Thursday if Ms. Miers ignores her subpoena and skips his hearing, based upon the White House’s assertion of executive privilege.

An argument that Ms. Miers has to testify “is certainly as tenable as that she doesn’t,” a University of Texas law professor, Sanford Levinson, says.

“If I were advising the congressional committees, what I would want to argue is that they have evidence that she was involved in what might have been criminal acts; that is, subordination of civil service hiring to unlawful considerations,” Mr. Levinson said.

George Washington University law professor Jonathan Turley said the White House “could not have picked worse ground” on which to fight executive privilege.

Many of the communications involve political operatives outside the White House; the White House already has offered to disclose the information and simply refused to do so under oath or with a transcript, and the issue is not in the sensitive areas of national security or diplomacy.

Legal scholars say it’s unlikely the White House and Congress are bound for a head-on collision.

“We’ve been here many, many times before. This is not out of the ordinary,”the former assistant attorney general for legal policy during Bush’s first term, Viet Dinh, said. “For me, the only surprising thing is he’s waited this long to finally exert executive privilege.”

No president has gone as far as mounting a court fight to keep his aides from testifying on Capitol Hill, but court is just where the battle could end up absent the usual negotiated agreements of the past.

President Ford testified on Capitol Hill about his pardon of President Nixon.

President Clinton’s aides testified in the Whitewater investigations launched by congressional Republicans.

This dispute over Democratic claims that the firings were politically motivated has been simmering for months but the issue of executive privilege — how much information lawmakers can force presidents to disclose — is as old as the nation. Ever since George Washington refused to release his War Department correspondence, the executive and legislative branches have tussled over their authority.

“Ms. Miers has absolute immunity from compelled congressional testimony as to matters occurring while she was a senior adviser to the president,” White House Counsel Fred Fielding wrote in a letter to Ms. Miers’ lawyer, George T. Manning.

On Wednesday, another former White House aide under subpoena, a onetime political director, Sara Taylor, tried to answer some questions before the Senate Judiciary Committee but not others without breaching either the subpoena or Bush’s claim of executive privilege.

Both Ms. Taylor and Ms. Miers still face possible contempt citations.

Mr. Fielding based his advice to Bush on a Justice Department memo this week that quoted former officials — from a former Attorney General, Janet Reno, to the late Chief Justice, William Rehnquist, writing as an assistant attorney general — as saying the president and his immediate advisers are absolutely immune from congressional subpoenas.

The Democrats shot back that those documents referred only to White House advisers currently serving. Ms. Miers and Ms. Taylor left the White House earlier this year.

Contempt citations are rare. Since 1975, 10 senior administration officials have been cited but the disputes were all resolved before getting to court.

The political resolution of such disputes has sometimes favored the White House, such as when President Eisenhower kept officials from testifying at Senator McCarthy’s hearings. Other times, Congress wins, such when Nixon reluctantly let aides testify about the Watergate break-in.

A Library of Congress expert on presidential powers, Louis Fisher, has said the dispute over the fired prosecutors is not one that’s likely bound for the federal courthouse.

The law is unsettled in the area. A 1974 Supreme Court decision held the president could not withhold the Watergate tapes from federal prosecutors. But the high court made it clear it wasn’t getting into whether presidents may refuse demands from Congress.

Both sides benefit from such uncertainty because it forces political concessions.