In December 2008, Virginia-based deputy sheriff Arthur Weston Staples III received a visit at home from police investigating claims he had traded child pornography images online. The former Vietnam vet, who had no previous offenses, was eventually sentenced to more than 17 years in prison after investigators found 400 to 600 illegal images, according to court documents.

The 210-month sentence can be considered modest compared with the life sentences dished out in many child pornography convictions. But in a twist, Staples was also ordered to pay $3.68m for his possession of a single picture taken more than 10 years earlier of a girl being severely sexually abused when she was eight years old. The restitution was awarded to “Amy,” the pseudonym of the victim, who is now 21 and has filed almost identical claims in some 600 other federal prosecutions over the past 18 months.

Over the same period, a separate survivor of sex abuse images identified only as “Vicky” has submitted some 80 claims under the same law, known as the Mandatory Restitution for Sexual Exploitation of Children Act.

Courts have responded to the flood of restitution requests with widely varying rulings. In sharp contrast to the outcome in Staples's case, the federal judge presiding over a separate child pornography trial in the Eastern District of Texas refused to award any restitution at all, even though two of the illegal images defendant Doyle Randall Paroline admitted to possessing were identified as depicting Amy. That ruling is now on appeal before the US Fifth Circuit Court of Appeals, where oral arguments are scheduled for this Thursday.

The new legal maneuver comes as the internet has fundamentally changed the way child abuse images are trafficked. It also comes as federal prosecutions for child pornography have skyrocketed over the past 15 years. In 1995, there were 50, according to the National Center for Missing and Exploited Children. Last year, there were almost 2,500.

The photographs and videos of Amy – which were shot and originally published by the girl's uncle – have taken on a life of their own over the past decade, becoming a staple known as “the Misty series” in child predator circles. They depict some of the most depraved images imaginable, including fellatio, cunnilingus, and anal and vaginal penetration.

There are at least 730 federal prosecutions that involve images from the series, according to court documents. The National Center for Missing and Exploited Children has said the pictures have been actively traded since 1998 in more than 3,227 cases.

New York attorney James Marsh, who represents Amy, hired a psychologist and economist to evaluate her and calculate the damage that has stemmed from her abuse and the continuing distribution of the images documenting it. Accounting for lost wages, counseling and lawyer fees, they settled on a price of $3.37m.