While the U.S. Supreme Court appears poised to keep a widely used abortion pill available for now, some conservative justices have signaled an interest in considering whether a 151-year-old indecency law should prevent American women from receiving the drug by mail.

A majority of the court indicated during arguments Tuesday that they weren’t convinced a group of conservative doctors had legal standing to oppose Food and Drug Administration approval of mailing doses of mifepristone, a drug now used in more than half of all abortions. But Justices Clarence Thomas and Samuel Alito asked about the reach of the Comstock Act, a law passed in 1873 that prohibits mailing of "lewd materials” and drugs used to terminate a pregnancy.

The prospect of a future challenge based on that law, which hasn’t been enforced for decades, is a concern for abortion advocates. They’ve faced a widening battle since the high court overturned the landmark Roe v. Wade decision in 2022, clearing the way for tougher restrictions or bans on the procedure in Republican-led states.