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.

In Texas, Florida, and more than a dozen other states, users who try to access the world’s largest pornography website are greeted by a surprising sight: a message on a black screen telling them they’re blocked because of the actions of their state legislature.

A Texas anti-pornography law is going before the Supreme Court on Wednesday in a collision of free speech rights, regulation of online content and the protection of children. Texas is among more than a dozen states with similar laws aimed at blocking young children and teenagers from viewing pornography.

Texas and 18 other states have recently enacted laws requiring pornography websites to verify the ages of their visitors.

A Texas appeal over age verification for accessing sexual content online raises important constitutional questions involving the First Amendment.

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

A majority of the Supreme Court signaled Wednesday that Texas may be permitted to require some form of age verification for pornographic sites, but left open the possibility that deeper First Amendment questions may not be resolved immediately.