Per the USFA, 4/6/17:
USA Fencing Sanctioned Events to Require at Least One Rated Referee Beginning Aug. 1, 2017
In Chapter 2.1 of the Athlete Handbook, it states that beginning August 1, 2017 that all USA Fencing sanctioned events must have at least one rated referee.
Also, as of January 1, 2017, all tournament officials must be compliant with the USA Fencing Safe Sport Policy, including maintaining a current background check and completion of the free online Safe Sport training course. Per the USFA, tournament officials include referees, bout committee, armorers, and floor managers.