According to Section 455-B(3) of Title 28 of the U.S. Code, justices must disqualify themselves in cases where they have “served in governmental employment and in such capacity participated as counsel, adviser, or material witness concerning the proceeding or expressed an opinion concerning the merits of the particular case or controversy.” In United States v. Gipson, the Tenth Circuit held that judges must recuse themselves if they have “previously taken a part, albeit small, in the investigation, preparation, or prosecution of a case.” Other courts have suggested that, merely by virtue of a lawyer’s position as the head of an office during the preparation of a case, he or she is disqualified to sit as a judge on that case. For example, several U.S. Circuit Courts of Appeal have held that U.S. attorneys who later become judges must recuse themselves from any proceeding that had been pending in any way in their offices, even if they were not substantively involved.
LOL