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.

The law, meant to shield minors from sexual materials on the internet by requiring adults to prove they are 18, was challenged on First Amendment grounds.

U.S. Supreme Court justices expressed worries on Wednesday over the availability of online pornography to minors as they weighed the legality of a Texas law that requires pornographic websites to verify the age of users,