It could possibly be used as evidence at trial (admissibility would be decided by the judge), but it wouldn’t be the same as a confession to the police, since the penitent would not have been mirandized prior to the confession and would not have willingly waived their right to remain silent.
Only the penitent can freely reveal the contents of a Confession. The priest must value the Seal above his life. The confessions of a penitent should be as a sacred and as secret as though they were uttering their sins to God in the solitude of their thoughts. The person might choose to tell others, but God does not.
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