Texas bookstores have joined with national organizations to sue in federal court over a new Texas law that requires a rating system for books in schools and seeks to ban sexually explicit books from public school libraries.The American Booksellers Association and other national groups were joined by BookPeople in Austin, Blue Willow Bookshop in Houston and others in filing the suit, saying the law, due to take effect on Sept. 1, “is unrealistic, limits students’ reading options and narrows libraries’ book selections,” according to the Statesman.Named as defendants in the suit are several state agencies, including the Texas Education Agency,