Justus (560), along with his brother Clement and Ottaviano, is one of the three patrons of the diocese of Volterra, and was involved in the Schism of the Three Chapters.

[5] In the Carolingian period it belonged to the Marquisate of Tuscany; with the approval of Henry, son of Frederick Barbarossa, its governance passed into the hands of the bishop, until his temporal authority was suspended by the commune.

In the wars or factions of the 13th century, Volterra, being Ghibelline, was continually embroiled with the Florentines, who captured it in 1254, but won permanent control only in 1361.

[6] Bishop Guido Servidio (1574–1598) presided over a diocesan synod in the cathedral of Volterra on 8–10 May 1590, and had the constitutions of the meeting published.

[9] A diocesan synod was held by Bishop Ottavio del Rosso (1681–1714) in the cathedral on 14–15 June 1684, the acts of which were published.