House Democrats won an initial victory in their oversight battle against President Bush when a federal judge ruled Thursday that current and former White House officials were wrong not to comply with House Judiciary Committee subpoenas for documents and testimony about the 2006 firings of nine U.S. attorneys.

But the immediate practical effect is likely to be limited. The Justice Department is expected to appeal the ruling by U.S. District Judge John D. Bates, and the case is unlikely to be resolved until after Bush has left office.

Still, Democrats hailed the ruling as an important rebuke of the Bush administration’s aggressive assertions of executive power in resisting congressional oversight.

Bates ruled that White House Chief of Staff Joshua B. Bolten could not simply refuse to hand over any White House documents related to the firings. He also ruled that former White House counsel Harriet Miers could not avoid physically appearing before the committee.

Judiciary Chairman John Conyers Jr., D-Mich., called the ruling a “ringing reaffirmation of the fundamental principle of checks and balances and the basic American idea that no person is above the law.”

Conyers said, “We hope that the defendants will accept this decision and expect that we will receive relevant documents and call Ms. Miers to testify in September.”

Meanwhile, Dana Perino, the White House press secretary, said of the ruling: “We disagree with it, and I’m not going to prejudge a decision whether or not to appeal.”

The Judiciary Committee filed a lawsuit earlier this year after Miers and Bolten refused to comply with subpoenas because Bush invoked executive privilege. Miers was subpoenaed to provide both testimony and documents; Bolten was subpoenaed for White House records related to the firings.

“The executive’s current claim of absolute immunity from compelled congressional process for senior presidential aides is without any support in the case law,” wrote Bates, a judge in the U.S. District Court for the District of Columbia.

Bates wrote, “The Supreme Court has reserved absolute immunity for very narrow circumstances, involving the president’s personal exposure to suits for money damages based on his official conduct or concerning matters of national security or foreign affairs.”

Bates said that Miers is legally required to testify before the committee but can decline to answer individual questions on executive privilege grounds. The judge ordered Miers and Bolten to produce “non-privileged documents” that were subpoenaed, as well as a list of documents they are withholding on privilege grounds.

That means that although Miers eventually might have to appear, she can refuse to answer questions by citing executive privilege. And Bolten and Miers can still withhold documents on privilege grounds. All that likely would leave Bates to sort out individual privilege claims. And a likely Justice Department appeal would prevent even that from happening anytime soon.

The subpoenas will expire at the end of the 110th Congress. But if Democrats retain control of the House in November, the Judiciary Committee is expected to reissue them next year.

Lamar Smith of Texas, the Judiciary Committee’s ranking Republican, agreed that the ruling was important in terms of affirming congressional oversight powers. But in a statement, he said, “While I am pleased the court ruled in favor of Congress in this case, I remain concerned that the information requested by House Democrats does not merit a constitutional showdown between Congress and the administration.”

The ruling has implications for former White House adviser Karl Rove, who refused to comply with a committee subpoena to appear at a July 10 hearing to testify about allegations that the Justice Department had engaged in politically motivated prosecutions of Democratic officials, including former Alabama Gov. Don Siegelman.

Rove’s attorney, Robert Luskin, who cited executive privilege grounds in that matter, declined Thursday to comment on Bates’ ruling. The committee voted Wednesday to approve a contempt-of-Congress citation against Rove.

On Thursday, Patrick J. Leahy, D-Vt., chairman of the Senate Judiciary Committee, sent letters to Luskin and White House Counsel Fred Fielding setting an Aug. 7 deadline for a reply indicating when Rove and Bolten would appear to testify and provide documents. Leahy also sent a letter to Attorney General Michael B. Mukasey suggesting the Justice Department withdraw memorandums justifying the White House’s noncompliance with the subpoenas.

The Judiciary Committee is not the only House panel that has issued subpoenas that Bush has sought to deflect with an executive privilege claim.

The Oversight and Government Reform Committee has subpoenaed Mukasey to produce FBI reports of an interview of Vice President Dick Cheney regarding the disclosure of CIA agent Valerie Plame’s covert status. The committee also issued separate subpoenas for documents regarding two controversial environmental issues.

House Speaker Nancy Pelosi, D-Calif., said the ruling is “very good news for anyone who believes in the Constitution and the system of” checks and balances.

Pelosi said the ruling “will strengthen our hand as we go forward.’’

Minority Leader John A. Boehner, R‑Ohio, said he was sure the administration would appeal the District Court ruling, meaning the case will drag into next year. By then, Boehner predicted, it will become moot, because Bush will leave office in January 2009.

The Judiciary panel resorted to its lawsuit after Mukasey refused to refer a House contempt citation against Bolten and Miers to a federal grand jury, as required under law.

Edward Epstein contributed to this story.