The Cheyenne-based attorney joined the Supreme Court in January. She filed a brief recusal memo in the Supreme Court on Thursday. Fox asked to be excused one day after the state filed for a rehearing in the case, in which the court ruled unconstitutional a controversial law stripping Hill of much of her power last year.
"I must recuse myself from participation in this case," Fox wrote in the memo filed Thursday.
Fox provided no explanation in the memo. Neither Fox nor Chief Justice Marilyn Kite was available for comment Monday; Supreme Court offices were closed for President's Day.
But records show Fox represented Rep. Rosie Berger, R-Big Horn, last year when Hill threatened to sue Berger over a legislative report the superintendent considered libelous. Such a conflict of interest could justify a justice's request to be excused from a case.
Court rules say if a justice is recused, the justice who participated in the original decision should sit in his or her place, if available.
The justices who originally heard the Hill case were Kite, Justice James Burke, Justice Michael Davis and retired Justices Barton Voigt and Michael Golden.
Justice William Hill recused himself from the Hill case when it was filed last year. He is married to Mary Kay Hill, a deputy policy director for Gov. Matt Mead, who is named in the lawsuit. Golden was appointed to fill Justice Hill's seat for the case.
It is unclear whether Golden will remain on the court to consider the state's rehearing petition or whether Kite will appoint someone else. Court rules give Kite the authority to appoint members of the judiciary to serve in place of any justice who is unable to.