Bluebook Rule (21st): 1.4
Law Review Typeface: Varies By Document Type
Rule 1.4 deals with the order of authorities within each signal. The main authority being cited, or whichever is most useful, if any, should always be cited first.
Previous versions of Rule 1.4 provided exhaustive, almost prescriptive details for how various specific authority types (constitutions, statutes, treaties, etc.) should be ordered when they are equally relevant or important. The current version of Rule 1.4 in the 21st Edition of the Bluebook abandons that approach. Instead, it simply advises that authorities "should be ordered in a logical manner," and separated by a semicolon.
Generally speaking, this will mean ordering the authorities based on three characteristics:
1) Type of authority;
2) Jurisdiction; and
3) Hierarchy and/or Chronology
When in doubt, consider consulting prior versions of Rule 1.4 (Bluebook 20th Edition or earlier). Also keep this change in mind when reviewing older citations for guidance, as the order of authorities within older citations was driven by more specific requirements.