President Bush's top advisers are not immune from congressional subpoenas, a federal judge ruled Thursday in an unprecedented dispute between the two political branches.

    The House Judiciary Committee wants to question the president's chief of staff, Josh Bolten, and former legal counsel Harriet Miers, about the firing of nine U.S. attorneys. But President Bush says they are immune from such subpoenas. They say Congress can't force them to testify or turn over documents.

    U.S. District Judge John Bates disagreed, saying there's no legal basis for that argument and that Miers must appear before Congress. If she wants to refuse to testify, he said, she must do so in person.

    "Harriet Miers is not immune from compelled congressional process; she is legally required to testify pursuant to a duly issued congressional subpoena," Bates wrote.

    He said that both Bolten and Miers must give Congress all non-privileged documents related to the firings.

    The ruling is a blow to the Bush administration's efforts to bolster the power of the executive branch at the expensive of the legislative branch. Disputes over congressional subpoenas are normally resolved through political compromise, not through the court system. Had Bush prevailed, it would have dramatically weakened congressional authority in oversight investigations.

    The administration can appeal the ruling. White House spokesman Tony Fratto and Justice Department spokesman Peter Carr said they were reviewing the court's opinion and declined immediate comment.

    Bates, who was appointed to the bench by Bush, issued a 93-page opinion that strongly rejected the administration's legal arguments. He noted that the executive branch could not point to a single case in which courts held that White House aides were immune from congressional subpoenas.

    "That simple yet critical fact bears repeating: the asserted absolute immunity claim here is entirely unsupported by existing case law," Bates wrote.

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    Associated Press reporter Laurie Kellman contributed to this story.