Upon the death of Pope Benedict VII in July 983, Emperor Otto II nominated Canepanova to the papal throne after the abbot Maiolus of Cluny refused the office.
Otto's death in December left the Pope without allies, and he was deposed and confined at Castel Sant'Angelo after the seizure of the papal throne by Antipope Boniface VII.
[6] The only extant document from John's pontificate is a bull that granted a pallium to Alo, the archbishop of Benevento; the action is indicative of Otto's political interests in southern Italy.
[6] His widow, the Empress Theophanu, immediately left Rome to travel to Germany to protect the interests of her infant son Otto III (r. 980–1002), leaving John isolated in the city without allies.
[6] Upon the return of Antipope Boniface VII from Constantinople in April 984 and his installation as pope by the influential Crescentii family, John was assaulted, deposed, and confined at Castel Sant'Angelo.