A trade group for the adult entertainment industry will appear at the Supreme Court on Wednesday in its challenge to a Texas law that requires pornography sites to verify the age of their users before providing access – for example, by requiring a government-issued identification. The law applies to any website whose content is one-third or more “harmful to minors” – a definition that the challengers say would include most sexually suggestive content, from nude modeling to romance novels and R-rated movies.