Did the 1983 Code of Canon Law change the law on celebrating/receiving the Eucharist in a state of serious sin?

Question

Canon 916 is the current canon governing each individual's obligation not to celebrate or seek to receive the Eucharist in a state of (unconfessed) serious sin:

916. Qui conscius est peccati gravis, sine praemissa sacramentali confessione Missam ne celebret neve Corpori Domini communicet, nisi adsit gravis ratio et deficiat opportunitas confitendi; quo in casu meminerit se obligatione teneri ad eliciendum actum perfectae contritionis, qui includit propositum quam primum confitendi. [vatican.va]

916. A person who is conscious of grave sin is not to celebrate Mass or receive the body of the Lord without previous sacramental confession unless there is a grave reason and there is no opportunity to confess; in this case the person is to remember the obligation to make an act of perfect contrition which includes the resolution of confessing as soon as possible. [vatican.va]

It is clearly a unification of two canons from the 1917 Code, canon 807 concerning the celebration of the Eucharist and canon 856 concerning its reception:

807. Sacerdos sibi conscius peccati mortalis, quantumvis se contritum existimet, sine praemissa sacramentali confessione Missam celebrare ne audeat; quod si, defciente copia confessarii et urgente necessitate, elicito tamen perfectae contritionis actu, celebraverit, quamprimum confiteatur. [via IntraText.com]

856. Nemo quem conscientia peccati mortalis gravat, quantumcunque etiam se contritum existimet, sine praemissa sacramentali confessione ad sacram communionem accedat; quod si urgeat necessitas ac copia confessarii illi desit, actum perfectae contritionis prius eliciat. [via IntraText.com]

Both 1917 canons speak of consciousness of mortal sin (Sacerdos sibi conscius peccati mortalis...; Nemo quem conscientia peccati mortalis...). By contrast, the 1983 canon speaks of consciousness of grave sin (Qui conscius est peccati gravis...).

Does the change in terminology, from "mortal sin" (peccati mortalis) in the 1917 Code to "grave sin" (peccati gravis) in the 1983 Code change the meaning of the canons in any way?

Answer 1

Commentating on the 1917 Code, Dom Augustine writes in his A Commentary on the New Code of Canon Law can. 856:

No one who is conscious of a mortal sin, no matter how sorry or contrite he may feel, is allowed to receive Holy Communion without having previously gone to confession. In case of urgent necessity, when no suitable confessor is at hand, such a one must make an act of perfect contrition before approaching the Sacred Table.

This canon we leave to moralists to explain, because it pertains to the court of consequence. We will only add that this law, no matter whether it be regarded as divine [cf. 1 Cor. 11:27,29] or ecclesiastical, is a grave one, as is apparent from the Council of Trent [cf. sess. 6, ch. 15]. Copia confessarii must be understood of any confessor with the necessary faculties who is not an accomplice of the penitent. Theologians say that the repugnance to, or impossibility of going to confession must be such as is not directly connected with the act itself. Urgent necessity of receiving Holy Communion exists when one has to fulfill the paschal obligation, and before contracting marriage.

The New Commentary on the Code of Canon Law p. 1170 on the 1983 Code says:

It is not for canon law to determine what sins, including transgressions of the ecclesiastical law itself, are grave and what sins are non-grave or venial.⁸⁹

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^{89. …canonical avoidance of distinctions between "grave" and "mortal" sins…}

Thus it seems "grave" and "mortal" sins are synonymous terms in Canon Law.