WASHINGTON — In filling four senior Justice Department positions Monday, President-elect Barack Obama signaled that he intends to roll back Bush administration counterterrorism policies authorizing harsh interrogation techniques, warrantless spying and indefinite detentions of terrorism suspects.

The most startling shift was Obama's pick of Indiana University law professor Dawn Johnsen to take charge of the Office of Legal Counsel, the unit that's churned out the legal opinions that provided a foundation for expanding President George W. Bush's national security powers.

Johnsen, who spent five years at the Office of Legal Counsel during the Clinton administration and served as its acting chief, has publicly assailed "Bush's corruption of our American ideals." Upon the release last spring of a secret Office of Legal Counsel memo that permitted the aggressive interrogations of terrorism suspects, she excoriated the unit's lawyers for advising Bush "that in fighting the war on terror, he is not bound by the laws Congress has enacted."

"One of the refreshing things about Dawn Johnsen's appointment is that she's almost a 180-degree shift from John Yoo and David Addington and (Vice President) Dick Cheney," Harvard University law professor Laurence Tribe said, referring to the main legal architects of the administration's approval of harsh interrogation tactics.

Obama also said that he'd nominate:

u David Ogden, a top Justice Department official during the Clinton administration, as deputy attorney general, the No. 2 figure under Attorney General-designate Eric Holder.

u Elena Kagan, the dean of the Harvard University Law School and a former Clinton White House aide, as solicitor general.

u Tom Perrelli, counsel to Clinton Attorney General Janet Reno from 1997 to 1999, as the associate attorney general who oversees civil matters.

The president-elect said he hoped the four appointees would restore "integrity, depth of experience and tenacity" to the lead federal law enforcement agency, which has been battered by scandal.

"This is a superb set of appointments," said Walter Dellinger, a Duke University law professor who headed the Office of Legal Counsel and served as solicitor general from 1993 to 1997. "These four are highly accomplished in the profession and bring a stature to the job that will allow them to say no to the president when no is the correct answer."