It’s tough getting a consensus on anything these days, but child sex abuse and human trafficking are generally considered indefensible crimes. So who’s defending them?

According to “I Am Jane Doe,” that would be Google. And Microsoft. And Facebook. And Yahoo.

Directed by Mary Mazzio (“Lemonade Stories,” “Underwater Dreams”) and coming to Netflix May 26 after a theatrical run earlier this year, the documentary advocates for victims of online trafficking while taking principal aim at the classified-ad website Backpage.com, a notorious venue for sex ads and transactions, many involving children. In its indictment of Backpage.com and the tech companies that are indirectly supporting the website, the film may also give a public relations boost to members of Congress working to tighten laws surrounding Internet liability. In doing so, “I Am Jane Doe” may be the rare social-issue documentary that has an effect on a social issue.

[‘I Am Jane Doe’: A disturbing look at Internet-enabled exploitation]

According to Section 230 of the 1996 Communications Decency Act, online service providers cannot be held liable for third-party content. But that means if someone sells a 13-year-old on its pages, Backpage says, it isn’t responsible. And so far, court after court has agreed — to the relief of First Amendment absolutists, and the Silicon Valley companies mentioned above, which support, financially, organizations defending Backpage’s position.

As the film explains — through the voices of victims, their mothers, their advocates and narrator Jessica Chastain — neither side is letting up.

Backpage was once part of Village Voice Media and is now owned by a Dutch firm, although founders Michael Lacey and Jim Larkin and chief executive Carl Ferrer have been named in the suits. “I Am Jane Doe” picks up the Backpage saga in 2010 with lawsuits filed by girls who were trafficked on its pages, and continues through a Senate subcommittee investigation led by Sen. Rob Portman (R-Ohio) in January, as well as criminal charges of pimping and money laundering brought by then-California Attorney General Kamala D. Harris, now a Democratic senator. It also focuses on the effort that has thus far made the most headway — a civil suit that continues in Washington state, piloted by lawyer Erik Bauer. Backpage will try to get that case dismissed during a summary judgment hearing Wednesday. A jury trial is scheduled for Oct. 9.

“I think we’ll kick their a–,” Bauer said from his office in Tacoma, Wash. His argument, which has since been adopted by other plaintiffs, was that because Backpage provided guidelines about how posters could sculpt their ads to evade law-enforcement scrutiny, it made itself culpable outside the scope of Section 230.

Some parties to the issue disagree vigorously — it’s not about sex trafficking, but about liability.

“People looking at different legislative remedies are going to have to look at the other consequences of those proposals,” said Emma Llanso, director of the Free Expression Project at the Center for Democracy and Technology, one of the groups that have filed friend-of-the-court briefs in support of Backpage. She said those consequences could include online censorship, a disincentive for providers to actually monitor their content (lest they open themselves to legal liability), and an invasion of the social media “that we all use every day.”

Google has contributed tens of millions toward eradicating human trafficking. So have many of the big tech companies. But according to a report issued Wednesday by Consumer Watchdog, a public interest organization in California, many of the same companies — including Facebook, Microsoft and Yahoo, but Google more than any other — have also contributed to the Center for Democracy and Technology and the Electronic Frontier Foundation. Dozens of scholars, institutions and public-interest groups, many supported by Google and other companies, have lobbied against an overhaul of Section 230, saying that it could change the nature of the entire Internet. The report also alleges that Google makes $1 billion a year off postings for unlawful material and services, from pirated movies to child porn to prostitution.

“If there’s going to be an amendment to keep websites from helping sex traffickers, the only way it’s going to happen is if Google doesn’t stand in the way” said Jamie Court of Consumer Watchdog. “There’s no reason they should except they fear it’s a slippery slope and they’ll be held liable one day for something less egregious than what Backpage is doing.

“What’s Google going to do?” Court asked. “Be evil?” (Google’s longtime corporate motto was “Don’t be evil.”)

Google would only say in an email, through a spokeswoman, “We have long contributed to many independent organizations because of their advocacy on a wide range of Internet issues, including privacy, surveillance reform and the open Internet. We will continue to use our technology to combat child sex trafficking and connect victims and survivors with the resources they need.” 

“I Am Jane Doe” is an unabashed victim-advocacy film and has followed a route previously traveled by “The Invisible War” (sexual assault in the military), “The Hunting Ground” (campus rape) and “Trapped” (the war against reproductive choice): It’s taken its social-issue argument directly to Congress.

Rep. Ann Wagner (R-Mo.) had been working for a year to draft a bill that would exclude sex trafficking from Section 230 protections, but used the occasion of a February congressional screening of “I Am Jane Doe” to announce the Allow States and Victims to Fight Online Sex Trafficking Act, which now has bipartisan support.

“This is a criminal issue,” said Wagner. “Opponents of this bill have been brilliant in shaping their opposition as a First Amendment issue, but that’s bogus and they know it.”

“Of course, we all believe in freedom of speech. At the time this [act] was written, people weren’t selling kids online, let alone Backpage,” said Cindy McCain, wife of Sen. John McCain and one of the anti-trafficking advocates who appears in the film, via email. “It’s not a freedom-of-speech issue, it’s a human rights issue.”

Wagner said she thought “I Am Jane Doe” would be instrumental in “helping drive this bill across the finish line.” Over the years, films like “An Inconvenient Truth” and “Food Inc.” have probably left a considerable long-term impression on their viewers, but those viewers were likely to be sympathetic before they bought their tickets. Convincing lawmakers is a different thing entirely.

“The film definitely has created some additional leverage on the Hill,” said Yiota Souras, senior vice president and general counsel at the National Center for Missing and Exploited Children, based in Alexandria, Va. “Mary gave a voice to what a lot of attorneys and nonprofit organizations have been working on for years.”

Portman agreed. “We need to raise awareness about it, and that’s what this film does,” he said, adding that earlier this year, the members of his Senate Permanent Subcommittee on Investigations, who include Sens. John McCain (R-Ariz.), Heidi Heitkamp (D-N.D.) and Claire McCaskill (D-Mo.), “were able to show that [Backpage] knowingly tried to take out evidence of criminality to increase their own profits.” He was looking forward to drafting legislation that “narrows” Section 230.

“I think the tech community is willing to work with us,” he said, “but they are understandably concerned that if you go too far it will affect the ability to have a free Internet. We all get that — we’re not trying to shut down the Internet. What we’re trying to do is make it work better and safer.”

Mazzio simply hopes her film will spare a few children the horrors recounted in the film.

“There’s a cultural view of these crimes that says ‘It’s kind of sorta prostitution, and what’s the big deal about prostitution?’” Mazzio said. “You hear about a kid found in a dumpster and you say, ‘Oh, that poor troubled kid.’ … But the scope of this problem shows it’s simply not reality.”