By the 1920s, roughly 30 U.S. states had adopted a clergy privilege, often showing as much or more solicitude for the penitent as for the priest or pastor. “Unless the person confessing or confiding waives the privilege,” as the New York provision puts it, “a clergyman, or other minister of any religion or duly accredited Christian Science practitioner, shall not be allowed to disclose a confession or confidence made to him in his professional character as spiritual adviser.”
The privilege comes with the very steep cost that some wrongdoers may go free if their confession can’t be used. But a wrongdoer may be more willing to confess if confessions are protected, in which case the spiritual adviser or the penitent’s own conscience may encourage him to face up to his wrongdoing voluntarily.
Almost the only exception to the clergy-penitent privilege is for child abuse.