A US judge is considering whether it is constitutional to have a law that protects the clergy of just one religious denomination from disclosing what is said to them in confession.

Delaware Superior Court Judge Mary Miller Johnston, who has served on the Judicial Ethics Advisory Committee to the Delaware State Bar Association and who is a member of the board of governors of Wesley Theological Seminary, is considering whether legislation should apply to elders in a Jehovah's Witnesses congregation.

Delaware currently protects Catholic priests from disclosing to police any child abuse or other crime disclosed to them in confession, and is not the only state to do so. The priest-penitent privilege is regarded in law in the US, UK and elsewhere as similar to the lawyer-client confidentiality privilege and usually protects ministers of all religions and denominations within those religions.

The Attorney General's Office filed a lawsuit against the Laurel Delaware Congregation of Jehovah's Witnesses last year alleging two elders failed to report a sexual relationship between an adult female member of the church and a 14-year-old boy, Delaware Online reported.

State law in Delaware says suspected child abuse must be reported immediately on a dedicated hotline unless the individual or organisation is told of the abuse in an attorney-client setting or "that between priest and penitent in a sacramental confession".

After the boy told his mother he was in a relationship with Katheryn Harris Carmean White, they met with elders and the elders said they would speak with Carmean White. They subsequently did this but did not call the state hotline, the lawsuit says. She was arrested in 2013 and is currently serving six years for third-degree rape, fourth-degree rape and child endangerment.

Francis McNamara, for the congregation, told Judge Johnston that White and her victim discussed the relationship in confidential meetings that were equivalent to a Catholic confession. Judge Jonston then questioned whether any conversation between a parishioner and church elder should be considered confidential and exempt from reporting. Deputy Attorney General Janice Tigani, for the state, said the meeting was not a sacramental confession.

The Department of Justice filed the civil lawsuit in May last year.