NEW YORK, Feb 8 (Thomson Reuters Foundation) - When Mary Mazzio first heard about middle-school girls from her hometown of Boston suing a website on which they had been sold for sex, the self-described "recovering lawyer" was blown away.
"What? Fifteen minutes from where I live?" the film director remembers thinking.
"How, in the U.S., is it legal to sell children?"
Soon enough, pouring over a copy of the court case, Mazzio was plunged into a corner of the internet she had not suspected even existed: the world of classified ads website, Backpage.com.
Until last month, when Backpage abruptly shut its "adult" section, abused minors were being sold on Backpage as "escorts", alongside second-hand laptops and kitchen appliances.
On Tuesday, Backpage was hit with lawsuits saying it promotes the crime by rewriting ads offering children for commercial sex.
Each year, some 100,000 to 300,000 children are at risk of being trafficked for commercial sex in the United States, according to the U.S. Department of Justice.
In 2013, Backpage made more than 80 percent of its revenue from commercial sex advertising in the United States, according to a U.S. Senate report released last month.
Though Backpage may have yielded to the pressures of government officials and campaigners, the sex trafficking victims and their mothers haven't forgotten how it turned a profit by running ads from their pimps offering the girls for money, Mazzio said.
In her documentary film, "I Am Jane Doe", Mazzio chronicles the stories of sex-trafficked teens who have embarked on quixotic legal battles against the online classified advertising website, among the world's largest.
Backpage could not immediately be reached for comment.
Jane Doe is the name given to anonymous legal parties in U.S. courts, such as the five sex-trafficked victims that are suing Backpage and whose stories form the film's narrative.
The characters wage uphill battles, with Backpage repeatedly triumphing in court by arguing it is hosting content, not creating it, and is thus protected from liability by the federal Communications Decency Act (CDA).
The CDA, passed in 1996, was intended to protect free speech online by removing liability for a newspaper, say, for libelous comments posted on their websites by readers. The law has since shielded social media and e-commerce sites from liability in a variety of lawsuits.
Mazzio, a former Olympic rower, said she was stunned by the perseverance the young protagonists had displayed in taking on such a big enterprise against all odds.
"What my Olympic training taught me is 'You know you just never give up, you never give up.' And you are going to suffer withering loss," she said in a telephone interview.
"These women are relentless."
Mazzio began her filming by tracking three Jane Does whose suit against Backpage had first caught her attention.
But it is another two victims, J.S. and M.A. as they are called in the film, around whom most of the narrative revolves.
In sit-down interviews, both reflected on the hair-raising abuses they had endured - from having been put on a "leash" by ruthless pimps with hard drugs to beatings and a stabbing.
J.S. is an articulate young woman from Seattle. In a pre-ordeal home video that appears in the film, she giggles as she describes herself as a dedicated violinist and soccer player with dreams of becoming a doctor.
Ominously, in the film's opening scene, her mother, Nacole, recounts how years earlier, she had "expected to pick her up around 5:30 from track practice," only to find that her daughter had run away.
M.A., a precocious St. Louis teen, "snuck out of the house with her friends to head back to the school party," says her mother in the film.
The teenage runaways, 15 and 13 respectively, are among 1.6 million homeless and run-away children in the United States, according to the film's narrator, Hollywood star Jessica Chastain. "Within hours of dropping off the radar, thousands of them will be sex trafficked, a polite term for being repeatedly raped."
For the remainder of the film, "I Am Jane Doe" takes the viewer on a dizzying journey from courthouse to courthouse where successive teams of lawyers unsuccessfully butt their heads against the CDA, only to fail and try again.
In interludes, the young women whose lives have been broken give voice, along with their mothers, to their roller-coaster emotions.
"These children are going up against not only Backpage, but entrenched corporate interest and federal judges to try and achieve justice. They're swimming upstream," said Mazzio.
"With the level of violence that they endured, for them to stand up, I felt I had an obligation to be behind them, to bring any force that I could to be right behind them - we would be charging in the battle with them," she told Thomson Reuters Foundation.
"I Am Jane Doe" opens in select U.S. cinemas on Friday.
Half its profits will be donated to organisations helping victims of child sex-trafficking, Mazzio said. (Reporting by Sebastien Malo @sebastienmalo, Editing by Lyndsay Griffiths. Please credit the Thomson Reuters Foundation, the charitable arm of Thomson Reuters, that covers humanitarian news, women's rights, trafficking, property rights, climate change and resilience. Visit news.trust.org)