WASHINGTON (AP) — In the biggest challenge to abortion rights in decades, the Supreme Court's conservative majority on Wednesday signaled they would allow states to ban abortion much earlier in pregnancy and may even overturn the nationwide right that has existed for nearly 50 years.

With hundreds of demonstrators outside chanting for and against, the justices led arguments that could decide the fate of the court's historic 1973 Roe v. Wade decision legalizing abortion throughout the United States and its 1992 ruling in Planned Parenthood v. Casey, which reaffirmed Roe.

The outcome probably wo...