When does art become child porn?

Not far from the strip joints of Soho is an image of a child having sex with an adult that can be seen for nothing any day of the week. The child is a boy of about 10 or 11, completely naked, his backside raised and partially turned to the viewer. The adult is a young woman, also naked. She is slipping her tongue into his mouth; he is squeezing her right nipple between his fingers. Not only is the [...]