Justice William Brennan (unanimous): “By dispensing with any requirement of knowledge of the contents of the book on the part of the seller, the ordinance tends to impose a severe limitation on the public’s access to constitutionally protected matter. For if the bookseller is criminally liable without knowledge of the contents, and the ordinance fulfills its purpose, he will tend to restrict the books he sells to those he has inspected; and thus the State will have imposed a restriction upon the distribution of constitutionally protected as well as obscene literature…. ‘Every bookseller would be placed under an obligation to make himself aware of the contents of every book in his shop. It would be altogether unreasonable to demand so near an approach to omniscience.’ And the bookseller’s burden would become the public’s burden, for by restricting him the public’s access to reading matter would be restricted. If the contents of bookshops and periodical stands were restricted to material of which their proprietors had made an inspection, they might be depleted indeed.”