Are the Orthodox who are in schism with Rome able to celebrate the sacrament of Reconciliation validly?

Are the Orthodox who are in schism with Rome able to celebrate the sacrament of Reconciliation validly?

The short answer is yes.

From a Catholic perspective the sacraments of the Eastern Orthodox Churches are valid and licit. Please allow me to explain.

The question of validity is rather simple to ascertain. In fact, the Catholic Church permits Catholics to receive communion in Orthodox Churches, when the sacraments are unavailable from Catholic ministers. Canon 844 implies that the sacraments are licit, otherwise Catholics would be forbidden to receive the sacraments in Orthodox Churches in times of necessity.

Here is what the Code of Canon Law has to say on this issue:

Can. 844 §1. Catholic ministers administer the sacraments licitly to Catholic members of the Christian faithful alone, who likewise receive them licitly from Catholic ministers alone, without prejudice to the prescripts of §§2, 3, and 4 of this canon, and can. 861, §2.

§2. Whenever necessity requires it or true spiritual advantage suggests it, and provided that danger of error or of indifferentism is avoided, the Christian faithful for whom it is physically or morally impossible to approach a Catholic minister are permitted to receive the sacraments of penance, Eucharist, and anointing of the sick from non-Catholic ministers in whose Churches these sacraments are valid.

§3. Catholic ministers administer the sacraments of penance, Eucharist, and anointing of the sick licitly to members of Eastern Churches which do not have full communion with the Catholic Church if they seek such on their own accord and are properly disposed. This is also valid for members of other Churches which in the judgment of the Apostolic See are in the same condition in regard to the sacraments as these Eastern Churches.

§4. If the danger of death is present or if, in the judgment of the diocesan bishop or conference of bishops, some other grave necessity urges it, Catholic ministers administer these same sacraments licitly also to other Christians not having full communion with the Catholic Church, who cannot approach a minister of their own community and who seek such on their own accord, provided that they manifest Catholic faith in respect to these sacraments and are properly disposed.

§5. For the cases mentioned in §§2, 3, and 4, the diocesan bishop or conference of bishops is not to issue general norms except after consultation at least with the local competent authority of the interested non-Catholic Church or community.

The Eastern Churches are to be governed on their own as they also have apostolic succession.

The Special Consideration of the Eastern Churches

These Churches, although separated from us, possess true sacraments, above all by apostolic succession, the priesthood and the Eucharist, whereby they are linked with us in closest intimacy. Therefore some worship in common (communicatio in sacris), given suitable circumstances and the approval of Church authority, is not only possible but to be encouraged.

16. Already from the earliest times the Eastern Churches followed their own forms of ecclesiastical law and custom, which were sanctioned by the approval of the Fathers of the Church, of synods, and even of ecumenical councils. Far from being an obstacle to the Church's unity, a certain diversity of customs and observances only adds to her splendor, and is of great help in carrying out her mission, as has already been stated. To remove, then, all shadow of doubt, this holy Council solemnly declares that the Churches of the East, while remembering the necessary unity of the whole Church, have the power to govern themselves according to the disciplines proper to them, since these are better suited to the character of their faithful, and more for the good of their souls. The perfect observance of this traditional principle not always indeed carried out in practice, is one of the essential prerequisites for any restoration of unity. - Decree on Ecumenism Unitatis Redintegratio

Nowhere will one see that the sacraments of the Orthodox Churches are illicit since the days of Vatican Council II.

The term licit/illicit is a term used by the Church internally for her own liturgical laws. The Orthodox administrate their own sacraments with their own rules of conduct. The Catholic Church does not govern Orthodox sacraments.

The requirement of the proper form is only prescribed on Catholics (can. 1117 CIC). More general: all only ecclesiastical laws bind only Catholics (can. 11 CIC) and not the Orthodox.

Given this, there should not be any concern about SSPX marriages being invalid during the time when they were in schism with Rome. They are within the jurisdiction of the Catholic Church, since they still claim to be Catholic.

Both Pope St. Paul VI and Patriarch Atheneagorus of Constantinople nullified the excommunications from 1472, which means that Romans are now technically in communion with Constantinople itself though most Greeks do not recognize this.

Was the excommunication against the whole Eastern Church?

Rome excommunicated Patriarch Michael Cerularius of Constantinople and all of his immediate clergy. It did not excommunicate the emperor, or the patriarchs of Alexandria, Antioch, or Jerusalem, or the bishops of any of the other Eastern churches (especially not in the Slavonic north or Russia). Nor did the Slavs or any of the other patriarchs ever excommunicate Rome. So, strictly speaking, Romans are still technically in communion with most of the Eastern Orthodox Church. And this is especially true because we formally healed the schism at Lyon II in 1274 and at Ferrara-Florence in 1439. Our present schism dates from 1472, when the Greeks renounced the union of Ferraea-Florence -- something the Slavic Churches never formally did. Also, in 1965, Patriarch Atheneagorus of Constantinople and Pope Paul VI nullified the excommunications from 1472, which means that Romans are now technically in communion with Constantinople itself though most Greeks do not recognize this. But, technically, there is no reason why we should not be in full communion today. - The split of 1054 between the Orthodox and Catholics

Thus their sacraments are valid and licit.

More information may be gleaned from the following articles:

According to Roman Catholicism, was the 1054 excommunication of the Patriarch of Constantinople valid, in light of Leo IX's death?

Joint Catholic-Orthodox Declaration of His Holiness Pope Paul VI and the Ecumenical Patriarch Athenagoras I (December 7, 1965)