Excommunication is a medicinal penalty of the Church. Its purpose is not necessarily to obtain justice or satisfaction but is meant to awaken an individual’s conscience to repentance (canon 1312 & 1331).
Excommunication can either be imposed by the competent authority (usually a bishop) through a canonical process. In such cases, the action would be mentioned in canon law and the code would call for the competent authority to punish with a “just penalty.” If the competent authority felt in those specific circumstances a just penalty would be excommunication, he could then issue the decree.
The other way it can be imposed by canon law itself when certain actions take place. This one is called latae sententiae or “automatic” excommunication. Automatic excommunication happens when someone commits an act that is specifically punished in canon law by a penalty of automatic excommunication.
The 1983 Code of Canon Law attaches the penalty of automatic excommunication to the following actions:
- Apostates, heretics, and schismatics (can. 1364)
- Desecration of the Eucharist (can. 1367)
- A person who physically attacks the pope (can. 1370)
- A priest who in confession solicits another to violate the sixth commandment (can. 1378)
- A bishop who consecrates another bishop without papal mandate (can. 1382)
- A priest who violates the seal of the confessional (can. 1388)
- A person who procures an abortion (can. 1398)
- Accomplices who were needed to commit an action that has an automatic excommunication penalty (can. 1329)
In order for the penalty to be considered to apply, certain conditions must be met (can. 1323):
- The individual must be at least sixteen years old.
- The individual must know that his action was a violation of Church law.
- The individual must have acted freely without threat of force or grave fear, have the use of reason, and not have acted mistakenly.
Unless the canon reserves removal of the penalty to the Holy See, the local ordinary can remit the excommunication, or he can delegate that authority to the priests of his diocese (which most bishops do in the case of abortion).
By and large, automatic excommunications are not known to the public. Unless the individual committed the action in a public manner that would cause the local ordinary to issue a statement about the automatic excommunication, the burden is on the offender to confess the sin and seek the removal of the penalty.
An excommunicated person is not to receive the sacraments. However, if he does so in violation of the law, the sacraments are valid. An excommunicated person who marries has illicitly but validly received the sacrament. In such circumstances the grace of the sacrament would be of no effect, since the person is in a state of mortal sin. In the case of confession, the sacrament would be invalid because all mortal sins must be confessed for a valid confession (CCC 1456), and if the individual withholds the action(s) that incurred automatic excommunication, he’d be withholding a mortal sin.