The justices appeared skeptical of a challenge to the law brought by an adult-content industry group, producers of pornographic material and a porn actress.

The adult entertainment industry has said the law, which requires sites to verify that users are over 18, violates its free speech rights.

The Supreme Court seems open to a Texas law aimed at blocking kids from seeing online pornography. But the justices could still send it back to a lower court for more consideration of how the age verification measure affects adults’ free-speech rights.