He served successively as a university professor, priest, prior, archbishop, cardinal, apostolic legate and diplomat.
[2] He visited the kingdoms of the Iberian peninsula, including Portugal, as papal legate between 22 February 1228 and 3 January 1230.
[2][5] There he preached the crusades, held a synod in Lleida in 1229 and determined the boundary between the dioceses of Sigüenza and Osma.
[2] John may have become dean of the Sacred College in January 1230, as the most senior cardinal-bishop after the death of Pelayo Gaitán.
John is sometimes said to have been one of the papal negotiators, alongside Thomas of Capua, in the talks with Emperor Frederick II that resulted in the Treaty of San Germano (1230) and ended the War of the Keys.