Q: Can a non-Catholic go to Confession?
A: Yes, under specified conditions. Confession is one of three sacraments which canon 844 allows non-Catholics to receive in specified circumstances:
“844:3 Catholic ministers may licitly administer the sacraments of penance, Eucharist, and anointing of the sick to members of the oriental churches which do not have full communion with the Catholic Church if they ask on their own for the sacraments are properly disposed. This holds also for members of other churches which, in the judgment of the Apostolic See, are in the same condition as the oriental churches as far as these sacraments are concerned.
“844:4 If the danger of death is present or other grave necessity, in the judgment of the diocesan bishop or the national conference of bishops, Catholic ministers may licitly administer these sacraments to other Christians who do not have full communion with the Catholic Church, who cannot approach a minister of their own community, and on their own ask for it, provided they manifest Catholic faith in these sacraments and are properly disposed.”
The first paragraph applies principally to Eastern Christians (those in the Eastern Orthodox Churches, the Coptic Church, the Abyssinian Church, the Armenian Church, etc.) and states that they can receive confession, anointing, and the Eucharist if they ask for them and have the proper dispositions (which is also required of Catholics). Other communions may also share this if they are judged by the Vatican to have the same status concerning these sacraments as the Eastern churches.
The second paragraph applies principally to Protestants and adds several additional conditions because these churches do not have the same sacramental status as the Eastern ones. Most notably, “they [must] manifest Catholic faith in these sacraments,” meaning they must believe about them what Catholics do — e.g., that they are sacraments, that confession forgives sins, that anointing conveys spiritual and (if it is conducive to salvation) physical grace to the recipient, that Christ is Really Present in the Eucharist, etc.
A point has to be made about this because most Protestant denominations (virtually all, in fact) do not teach these things, whereas the Eastern Churches do and so belief in these things can be presumed for Eastern Christians (though, of course, if an Eastern Christian denied any of these things to a Catholic priest, the priest would need to refuse the sacrament to prevent them from profaning it).
Regarding the sacrament of confession, a Protestant who believes in it could receive it in a grave situation since virtually none of the Protestant churches have the sacrament of confession, making it impossible for him to approach one of his own ministers for it.
There is also another situation (in the United States, at least) in which a non-Catholic Christian can go to confession, and that is when he or she is in the process of converting to the Catholic faith. The National Statutes for Catechumenate (passed by the U.S. National Conference of Catholic Bishops November 11, 1986) states:
“36. The celebration of the sacrament of reconciliation with candidates for reception into full communion is to be carried out at a time prior to and distinct from the celebration of the rite of reception.”
Non-Christians and those who share the Christian faith but who have not been baptized cannot receive confession since baptism is the door to the rest of the sacraments. In fact, the function of confession is to restore the grace which was originally conferred on a person in baptism but which has sense been lost through (mortal or venial) sin. The early Church Fathers thus called confession “the second plank after the shipwreck,” the shipwreck being the sin in which we are born, baptism being the first plank which we may grab hold, and confession being the second plank we may grab hold if we let go of the grace of the first. Thus only baptized people can go to confession. If a person isn’t baptized, his first job is to get that sacrament.