Canon Law states that a Catholic priest must have faculties (permission from Church authority) to validly administer the Sacrament of Confession:
“Can. 966 §1. The valid absolution of sins requires that the minister have, in addition to the power of orders, the faculty of exercising it for the faithful to whom he imparts absolution.”
So a priest who lacks faculties cannot validly absolve from sin — unless the penitent is in danger of death:
“Can. 976 Even though a priest lacks the faculty to hear confessions, he absolves validly and licitly any penitents whatsoever in danger of death from any censures and sins, even if an approved priest is present.”
So if a priest is a schismatic, such as the priests of SSPX or any new schismatic group that might arise in opposition to Pope Francis, the priest cannot hear your confession validly.
However, this presents a doctrinal problem on the question of the Orthodox Churches. The Greek Orthodox Church, the Russian Orthodox Church, and similar Churches have all seven sacraments. This point is clear from the teachings of Vatican II and a subsequent clarification from the CDF during the pontificate of Pope Benedict XVI: Clarification on the Doctrine of the Church
If they have all seven sacraments, then do their priests validly absolve, even when the danger of death is not present, without faculties? Or can we say that these separated Churches have the ability, as members of the one true Church (despite the separation), to grant faculties?
[Updated 11 Aug 2015 — see my post Are the Sacraments of Marriage and Confession Valid in the SSPX?]
God desires all human persons to be saved, and so He has established and formed the seven Sacraments in such a way that they are not fragile and do not easily become invalid.
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