''My job involves not only an oath, but also a pledge, which I now give you,'' Mukasey told the 110,000 Justice employees nationwide, some of whom watched on the department's internal TV system.
''And that is to use all of the strength of mind and body that I have to help you to continue to protect the freedom and the security of the people of this country, and their civil rights and liberties, through the neutral and evenhanded application of the Constitution and the laws enacted under it.''
He said he would ''ask myself in every decision I make whether it helps you to do that, to take the counsel not only of my own insights but also of yours, and to pray that I can help give you the leadership you deserve.''
Mukasey, 66, inherits a Justice Department struggling to restore its independent image with more than a dozen vacant leadership jobs and little time to make many changes before another president takes office. He now has 14 months to turn it around after almost a year of scandal that forced Gonzales to quit and cast doubt on the government's ability to prosecute cases fairly.
An internal Justice inquiry is investigating charges that, under Gonzales, politics were allowed to influence decisions about prosecuting cases or hiring career attorneys. The allegations stemmed from an ongoing congressional inquiry of last year's firings of nine U.S. attorneys, and prompted questions about Gonzales' honesty.
Gonzales did not attend the ceremony, which lasted only about 14 minutes and was kicked off by a reading of the Pledge of Allegiance by Mukasey's two young grandsons. Former attorneys general John Ashcroft and Richard Thornburgh were among those in the crowd, which also included GOP Senate Judiciary Committee members Arlen Specter of Pennsylvania, Lindsey Graham of South Carolina and Sam Brownback of Kansas.
The Senate confirmed Mukasey last week by a 53-40 vote, which critics noted marked the narrowest margin for an attorney general in 50 years. His confirmation snagged briefly after Mukasey refused to say whether he believes an interrogation tactic known as waterboarding is a form of torture.
Lasting only four minutes, Mukasey's comments aimed to calm the bruised department. He allowed himself a small smile as he stood before his staff after he was sworn in, then briskly launched into his speech.
''What each person here does, on a day-to-day basis, is law,'' Mukasey said. ''We don't do simply what seems fair and right according to our own tastes and standards.''
''We do law,'' he said, ''but the result is justice.''