He became a major negotiator, on the mandate of Pope Celestine III, in the divorce case between King Philip II of France and Queen Ingeborg of Denmark.
[6] On 11 November 1185, two weeks before the pope's death, eighteen cardinals, including Melior, subscribed a bull in Verona in favor of the monastery of S. Peter Lobiensis.
[8] The successful candidate, was Humbertus Crivelli, the Archbishop of Milan and Cardinal of S. Lorenzo in Damaso, "a violent and unyielding spirit, and a strong opponent of Frederick (Barbarossa)," in the words of Ferdinand Gregorovius.
[12] His successor, Alberto di Morra, a friend of the emperor, brokered an agreement which might lead to a papal return to Rome, but Gregory VIII reigned for less than two months, having only been able to move from Ferrara to Pisa.
When he was in Pisa with the papal court, as the new pope, Clement III was about to return to Rome, on 13 January 1188, he subscribed a bull Ego Melior presbiter cardinalis sanctorum iohannis et pauli tit.
[15] Monaco glides over the problem by writing carefully, "He became bishop of Massa Marittima, only to be designated during the pontificate of Celestine III legate to France, a position he held from 1193 to 1197;"[16] and Ganzer is sure that Melior later gave up the bishopric.
Pope Celestine placed them in the care of Cardinal Melior, his legate, who accompanied them to Pisa, Genoa, Marseille, and finally Poitiers.
[23] He ordered an assembly of the notables of his kingdom at Compiègne on 4 November 1193, at which he presented a genealogy which claimed to show that Philip was related to Ingeborg within the prohibited degrees of kinship.
The archbishop of Reims, the king's uncle, Cardinal Guillaume "aux blanches mains", pronounced the marriage uncanonical and dissolved.
[24] Pope Celestine was sufficiently disturbed that he quashed the divorce judgment, "contra ordinem juris prolatam,"[25] and sent his notary, the subdeacon Centius, as his legate,[26] with letters for the king.
[27] On 23 July 1194, the Constable of France, Drogo de Merloto; Anselm, the Dean of S. Martin in Tours; and Ursio, the royal French Chamberlain; announced the agreement of yet another truce between the perpetually warring houses of Plantagenet and Capet.
[30] In a later letter, written by the chancellor Andreas to Archbishop Absalon of Lund in 1196, he recapitulates his troubles of the previous year, and adds that, on 7 April 1196, the archbishop of Sens, the bishop of Arras, the abbots of Cîteux and of Clairvaux, and Magister Petrus the precentor of Paris, were to act as judges delegate of the pope and examine the case of Philip and Ingeborg; they were to induce the king to take back the queen.
If they were to fail, then on the second Sunday after Easter, 5 May 1196, Cardinal Melior, on the mandate of the pope, was to assemble a council of the archbishops of Reims, Sens, and Tours, and the bishop of Bourges and their suffragans, along with the papal notary, were to induce the king to take back his wife.