An excommunication is said to be null when it is invalid because of some intrinsic or essential defect, e.g. when the person inflicting it has no jurisdiction, when the motive of the excommunication is manifestly incorrect and inconsistent, or when the excommunication is essentially defective in form. Excommunication is said to be unjust when, though valid, it is wrongfully applied to a person really innocent but believed to be guilty. Here, of course, it is not a question of excommunication latæ sententiæ and in foro interno, but only of one imposed or declared by judicial sentence. It is admitted by all that a null excommunication produces no effect whatever, and may be ignored without sin (cap. ii, de const., in VI). But a case of unjust excommunication brings out in a much more general way the possibility of conflict between the forum internum and the forum externum, between legal justice and the real facts. In chapter xxviii, de sent. excomm. (Lib. V, tit. xxxix), Innocent III formally admits the possibility of this conflict. Some persons, he says, may be free in the eyes of God but bound in the eyes of the Church; vice versa, some may be free in the eyes of the Church but bound in the eyes of God: for God’s judgment is based on the very truth itself, whereas that of the Church is based on arguments and presumptions which are sometimes erroneous. He concludes that the chain by which the sinner is bound in the sight of God is loosed by remission of the fault committed, whereas that which binds him in the sight of the Church is severed only by removal of the sentence. Consequently, a person unjustly excommunicated is in the same state as the justly excommunicated sinner who has repented and recovered the grace of God; he has not forfeited internal communion with the Church, and God can bestow upon him all necessary spiritual help. However, while seeking to prove his innocence, the censured person is meanwhile bound to obey legitimate authority and to behave as one under the ban of excommunication, until he is rehabilitated or absolved.