A new state law protecting clinics from legal fallout has allowed IVF treatments to resume — but clinicians and scientists in the United States who are working with human embryos are not totally reassured and fear that they will face an increasing number of legal and constitutional challenges.

An Alabama Supreme Court's ruling has torn open a long-simmering and emotionally charged debate about whether some aspects of in vitro fertilization represent a form of abortion and should be banned under religious principles. Christian opposition to abortion has long driven the debate over reproductive rights.