A few months ago, Adam Fuss, an internationally known fine art photographer, flew from New York to Costa Rica for one of his regular visits with his 7-year-old son, Arden. Arden's mother had absconded with the boy to Central America during a long-simmering custody dispute in the U.S., and he was living in a foster home run by the country's child protection agency while the local authorities figured out whether to return him to his father or not.