Backpage often points to the work of one scholar, danah boyd, of the Berkman Center for Internet and Society at Harvard University, who has written that the Internet provides new opportunities to intervene in the underground sex trade because it makes trafficking more visible than it once was.
McDougall lauded the systems Backpage already has in place to keep underage girls out of its adult ads.
"I think the company currently is better than anyone else out there. Our goal is to stay the industry leader, and to set the standard for everyone else to meet," she pledged.
McDougall took "Nightline" inside one of their screening rooms, the first time they have ever let reporters see how their filters function. According to McDougall, first an automated system screens for key words. Then, a real human being looks at each and every ad that goes up in the site's adult services section.
"Nightline" saw dozens of people at work, and Backpage says there are screening rooms in other locations, where in total, 80 percent of their employees are devoted to this kind of work.
Of course pimps and the underage girls they traffic often find ways to work around the safeguards, including using pre-paid gift cards instead of credit cards linked to an address.
"We're trying to stay ahead of them," McDougall said. "It's a cat and mouse game."
Backpage does work with law enforcement, responding to subpoenas and reporting about 400 ads a month to the National Center for Missing and Exploited Children.
Law enforcement officials from across the country told "Nightline" that they'd rather work with Backpage than be at odds with them. But many said the inescapable fact is that Backpage and other sites like it have made the buying and selling of sex exponentially easier than it was in the pre-Internet era.
"Before, you had to drive down the street. You had to build up the courage to make contact with someone. You had to stop out in public view," Oki said. "Now you're behind closed doors looking on your computer."
And he objects to the profits that Backpage and other sites like it are making off prostitution ads.
"I think it's wrong for any business or any Internet site to be profiting from the exploitation of women or children in the commercial sex industry," he said.
But Oki said he has mixed emotions on what the solution should be, noting that when Craigslist shut down its classified sex ads, the traffic moved to other sites.
"I'm kind of in the middle where the fact of, do I want to see these websites shut down, or remain open," he said.
Like many exploited minors, Megan had a troubled childhood fraught with family dysfunction and a sense of abandonment. She said she spent her early years searching for a father figure, as she bounced from relative to relative trying to find a stable home.
"I was used to getting kicked out. I was used to being, like, the troubled child," she said with tears in her eyes.
It all made her an easy and vulnerable target for the pimp who first approached her after she had spent the night sleeping at a bus stop.
"My first night, he took me to a hotel," she said. "And there was another girl there. And so, you know, he was like, 'Take a shower. Get ready and stuff. And we can take some pictures of you.'"