Complex sentence: The matrimonial nullity trial reforms of Pope Francis are reforms of the processes for matrimonial nullity trials of the Catholic canon law dealing with declaring the nullity of marriage that were given "motu proprio" by Pope Francis on 8 September 2015.
Split into simpler sentences: The matrimonial nullity trial reforms of Pope Francis are the reforms of the Catholic canon law governing the processes for matrimonial nullity trials. Theses reforms dealing with declaring the nullity of marriage were given "motu proprio" by Pope Francis on 8 September 2015.