The secrecy of the confessional in the Roman Catholic Church is so sacrosanct that any priest who violates it is automatically excommunicated.

In Washington State, a new law requiring clergy to break the seal when child abuse has been revealed has kindled a heated battle involving the state, the Roman Catholic Church and the Justice Department.

The legislation, signed into law last week by Gov. Bob Ferguson, a Democrat, requires members of the clergy to report child abuse or neglect to authorities, even if that knowledge arises during the sacrament of confession. It has outraged many Catholics in the state, and across the country.

“This law is a clear intrusion into the practice of our Catholic faith,” said Archbishop Paul D. Etienne of Seattle. “The state is now intruding into the practice of religion, and if they’re allowed to get away with that, where do we draw the line?”

The Justice Department apparently agrees. On Monday, the department announced it was opening a civil rights investigation into the law, which it called “anti-Catholic.” The investigation will focus on the law’s “apparent conflict” with religious freedom under the First Amendment.

Clergy are considered mandated reporters in a majority of states, meaning they are legally obligated to report to authorities if they suspect a child is being abused. In most states, however, the state reserves protections for the clergy-penitent relationship. In seven states, including New Hampshire and West Virginia, there is no such exception. (In Tennessee, the privilege is denied only in cases of child sexual abuse.) It’s not clear that any priests have been prosecuted or penalized in those states over failing to report abuse that they learned about during a confession.