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 on Wednesday seemed open to upholding a Texas law requiring age verification for accessing pornography online, though the debate turned murkier on the standard of scrutiny that should be applied to it and similar laws in more than a dozen states.