A three-judge panel in the 5th U.S. Circuit Court of Appeals upheld a preliminary injunction saying Mississippi cannot enforce a law banning abortions once a fetal heartbeat is detected.
Thursday's panel sided with District Judge Carlton Reeves, who first blocked the "heartbeat" law last May.
Jackson Women's Health Organization, the clinic that challenged the state law, said in court filings that cardiac activity in a fetus begins at six weeks, before most women know they're pregnant. Meanwhile, the state of Mississippi argues it can begin between six and 12 weeks.
The ruling cited a December decision that a 15-week ban was unconstitutional. It said: "All agree that cardiac activity can be detected well before the fetus is viable. That dooms the law. If a ban on abortion after 15 weeks is unconstitutional, then it follows that a ban on abortion at an earlier stage of pregnancy is also unconstitutional."
Similar "heartbeat" bans were passed in several other states last year. The bans are attempts to effectively overturn the Supreme Court's decision in Roe v. Wade, which guaranteed the legal right to abortion. Abortion rights advocates in other states have challenged those bans as well.