Judge David Souter, a quiet New Englander, was ceremonially sworn in at the White House as the 105th justice of the Supreme Court.

Chief Justice William Rehnquist administered the oath to Souter, 51, in the East Room before a large audience Monday that included President Bush, other Supreme Court justices, members of Congress and the Cabinet.In remarks before the ceremony, Bush said Souter had "demonstrated his lifelong devotion to principle, a straightforward, enduring principle, that the role he is assigned to is to interpret the laws and not to make them."

Bush quoted Souter's remarks during his confirmation hearings that judges must always be aware when they act that "some human life is going to be affected by what we do."

After taking the oath, Souter said, "I will try to pass on the constitutional authority that I received this afternoon. I will try to use it the best I can according to the light that God gives me."

Among those witnessing the ceremony was former Justice William Brennan, a leading liberal on the court for 34 years whose retirement opened the door for Souter's nomination. The 84-year-old former justice stood and was applauded by the audience when Bush singled him out in his remarks.

Bush selected Souter as his first nominee for the Supreme Court just three days after Brennan's retirement in late July. Souter is the court's youngest member and his lifetime appointment could easily run beyond 2015.

During his confirmation hearings, Souter deflected questions about his views on abortion and - despite strong opposition from some women's rights groups - the Senate confirmed him by a 90-9 vote on Oct. 2.

White House officials said Souter, a bachelor, actually was sworn in as a justice on Oct. 3 by an administrative officer at the court and Monday's event was ceremonial.

While he addressed very few major issues during his state court tenure and brief time of the federal bench, Souter was generally viewed as a moderate based on his confirmation testimony. But court observers see Souter as playing a potentially decisive role on the court.