WASHINGTON — In a groundbreaking case, the Supreme Court today held for the first time that religious employees of a church cannot sue for employment discrimination.

But the court’s unanimous decision in a case from Michigan did not specify the distinction between a secular employee, who can take advantage of the government’s protection from discrimination and retaliation, and a religious employee, who can’t.

It was, nevertheless, the first time the high court has acknowledged the existence of a “ministerial exception” to anti-discrimination laws — a doctrine developed in lower court rulings. This doctrine says the First Amendment’s guarantee of freedom of religion shields churches and their operations from the reach of such protective laws when the issue involves employees of these institutions.