Montesquieu

The law of Gundebald sub­sis­ted for a long time among the Burgundians, concur­rently with Roman law ; it was still in use there in the time of Louis the Debonaire ; Agobard’s let­ter lea­ves no doubt about that. Likewise, although the Edict of Pistres calls the land that had been occu­pied by the Visigoths the land of Roman law, the law of the Visigoths still sub­sis­ted there, which is pro­ven by the Synod of Troyes held under Louis the Stammerer in 878, which is to say four­teen years after the Edict of Pistres.

Subsequently, the Gothic and Burgundian laws peri­shed even in their own lands, through gene­ral cau­ses that made the per­so­nal laws of the bar­ba­rian peo­ples disap­pear eve­ryw­here.