The Council of Metz of 863 was arranged by Pope Nicholas I to discuss the divorce case of Lothar II, king of Lotharingia, and his wife Theutberga.
The council was mainly attended by Lothar II's supporters, and thus concluded the divorce case in his favour; this decision was later overruled by Pope Nicholas I who suspected foul play.
At this point the trial became of interest to the rest of the Carolingian empire and the Pope because Theutberga sought sanctuary with Charles the Bald, Lothar's uncle who ruled West Francia.
In November of 862, Nicholas wrote to the bishops assembled at Metz informing they had to investigate the divorce case against Theutberga and make a just ruling.
In his letter to the bishops and archbishops of the Carolingian empire instructs them all to assemble at Metz to discuss the divorce case as he thinks that Lothar II is at fault and needs to be brought to justice.
However, Lothar II was dominant, claiming he was already married to Waldrada, Theutberga was guilty and the decision from the Council of Aachen in 862 should be upheld.
Nicholas dismissed the document after consideration, as ‘a great deal in it was found to contain a profane baseness of language …which ensnared those archbishops for their frenzied trespassing beyond their episcopal rank'.
[11] Due to their heretical role in the Council of Metz and presenting Pope Nicholas I with the false document, Archbishops Gunther and Theutgard were excommunicated and deposed from office.