Mississippi’s claim that it can prohibit abortions after a fetus reaches 15 weeks gestation is foreclosed by long-standing U.S. Supreme Court precedent, an abortion provider told an appeals court.

Jackson Women’s Health Organization defended a federal court decision holding the 15-week abortion ban unconstitutional in the U.S. Court of Appeals for the Fifth Circuit April 5. The state appealed the decision in December 2018.

Mississippi, in its opening brief on appeal, told the Fifth Circuit that it is an open...