can be either [[latae sententiae]] (automatic, incurred at the moment of committing the offense for which canon law imposes that penalty) or ferendae sententiae (incurred only when imposed by a legitimate superior or declared as the sentence of an ecclesiastical court).

The Catholic Church teaches in the Council of Trent that "excommunicated persons are not members of the Church, because they have been cut off by her sentence from the number of her children and belong not to her