According to Title 28, Chapter I, Part 453 of the United States Code, each Supreme Court Justice takes the following oath:

"I, [NAME], do solemnly swear (or affirm) that I will administer justice without respect to persons, and do equal right to the poor and to the rich, and that I will faithfully and impartially discharge and perform all the duties incumbent upon me as [TITLE] under the Constitution and laws of the United States. So help me God."

http://uspolitics.about.com/od/usgovern ... fice_3.htm