Federal Rules of Appellate Procedure, Rule 44
Federal Rules of Appellate Procedure, Rule 44. Case Involving a Constitutional Question When the United States or the Relevant State is Not a Party
(a) Constitutional Challenge to Federal Statute. [Omitted]
(b) Constitutional Challenge to State Statute. If a party questions the constitutionality of a statute of a State in a proceeding in which that State or its agency, officer, or employee is not a party in an official capacity, the questioning party must give written notice to the circuit clerk immediately upon the filing of the record or as soon as the question is raised in the court of appeals. The clerk must then certify that fact to the attorney general of the State.