The American Civil Liberties Union announced on Monday that it had filed a lawsuit against the nation’s Roman Catholic bishops, arguing that their anti-abortion directives to Catholic hospitals hamper proper care of pregnant women in medical distress, leading to medical negligence.

The suit was filed in federal court in Michigan on Friday on behalf of a woman who says she did not receive accurate information or care at a Catholic hospital there, exposing her to dangerous infections after her water broke at 18 weeks of pregnancy.

In an unusual step, she is not suing the hospital, Mercy Health Partners in Muskegon, but rather the United States Conference of Catholic Bishops. Its ethical and religious directives, the suit alleges, require Catholic hospitals to avoid abortion or referrals, “even when doing so places a woman’s health or life at risk.”

The suit opens a new front in the clash over religious rights and medical care. The Catholic Church has fought against requiring all health plans to include coverage of contraception and is likely to call the new lawsuit an attack on its core religious principles.