WASHINGTON (WUSA9) — UPDATE: Backpage has been seized by federal law enforcement authorities

It's a sad and tragic fact: ordering a child for sex online can be as easy as ordering a pizza.

The biggest fighter of child sex trafficking, the National Center for Missing and Exploited Children, says most of those online orders are made on a site called Backpage. The website helps sell thousands of children for sex and makes millions off them, and it's all legal.

How is this so? That's exactly what documentary filmmaker, Mary Mazzio, asked, "How were these children sold repeatedly on a website 24/7, on the hour, by the hour? How was this happening in the United States of America?”

Mazzio made a popular film you can watch on Netflix, called "I Am Jane Doe."

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“This is not hidden in the deep, dark web. Click, and within 15 minutes...you can have a child delivered to your home as easy as ordering a pizza.”

Yvonne Ambrose's 16-year-old daughter Desiree was the light of her life. Ambrose, who is from Illnois, said she was smart, made good grades, and wanted to be a physician in the Air Force. One day in November 2016, Desiree disappeared. Four excruciatingly long weeks later, Yvonne’s phone rings.

"I got a phone call from the detectives in Markham police department, saying that we found your daughter, that was their verbiage, 'we found your daughter,' and I said 'great, you found her.' 'No, ma’am, we found her.' I don't remember much after that...I don't remember much, to have someone call you and say they found your daughter, it is a parent's worst nightmare," said Yvonne. "You pray that they don't get caught up with the wrong people. You keep them in every after school activity, she was involved in every sport. You can imagine she was a great kid, she helped feed the homeless, she was a great student and they found her.”

Ambrose said her daughter Desiree was murdered by a man who bought her on Backpage.

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“That man who purchased her from Backpage beat her, strangled her, raped her, and then cut her throat," she said.

She went on to say, “If I would have known what was really going on, on the internet...maybe I could have educated her differently but unfortunately she didn't make it.”

Every year, 300,000 children are lured into being sold for sex in this country, according to Ark of Hope For Children.

The average age of a victim is 15-years-old, according to Shared Hope International.

More than 70 percent are sold on Backpage, according to the National Center for Missing and Exploited Children.

U.S. Senate subcommittee report projects Backpage will make as much as $250 million next year.

How is this legal?

Backpage is protected by a 20+ year old law called the Communications Decency Act. All websites are, even the one you're reading this article on now. The act said sites can't be held liable for things other people post on them, like, let's say comments on articles.

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In this example, Backpage isn't liable for the ads on their site that sell children, because Backpage didn't place the ad, a third-party pimp did. Backpage just happens to give them a platform and make millions off the ads. So, lawsuits trying to make Backpage pay get dismissed.

That's why on January 11, 2018, Ambrose and hundreds of moms, survivors, filmmakers, and advocates went to Capitol Hill to fight to try and hold Backpage accountable.

They want Congress to pass a bill to amend the Communications Decency Act. There are actually two. One is called SESTA. It stands for Stop Enabling Sex Traffickers Act of 2017. It's a Senate bill. The other is called FOSTA. It stands for Fighting Online Sex Trafficking Act of 2017. FOSTA is set to be voted on Tuesday by the House.

UPDATE: With bill passing House, sex trafficking victims closer to justice

If it passes both houses, it would make it illegal to knowingly help sell underage children for sex. Then, victims like Ambrose could sue Backpage for restitution and potentially win.

Free speech advocates say that could open the door a crack for people to sue all sorts of websites for things other people post. Sasha Moss is a lawyer with R Street Institute, a think tank that believes in limited government.

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"Creating new laws with stronger burdens isn't necessarily the way to do it when we already have a toolbox full of ways prosecutors can get at the bad guy," she said.

On Capitol Hill, Lauren Hersh, a former prosecutor and founder of World Without Exploitation, is giving the advocates support in asking members of the House and Senate to support the bills.

In the front row of the hearing room, sat Kubiiki Pride. Her emotion was so raw, it could have overflowed any second.

Unlike Yvonne Ambrose, Kubiiki still has her daughter, but just barely. Her daughter, who wants us to call her M.A. was sold on Backpage in 2009. Kubiiki said she bought her back. Ever since, it’s been a struggle to keep her home and safe.

“It doesn't just damage the victim, it damages everything and everybody around it," she said. "I am truly an example, my family is truly an example of what this damage does.”

We tagged along as a tired Pride starts her fight. She said she's been fighting to make Backpage accountable for eight years.

"No, I’m not gonna give up, I made a promise to my daughter that I was going to keep fighting until the laws in the United States were changed because there's no reason kids should be sold for sex here," she said.

Pride explains just why this is so important to her.

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“You have to understand that at 13, my kid was taken and tied down and given drugs, like given a lot of drugs, she's been beaten, she's had so much done to her, I don't know how she will ever recover," she said.

There are a few people who helped make this canvassing day possible. One is Mazzio. She's also a former lawyer. She couldn't believe this was happening. Pride's daughter told her story in her film.

"We had no idea that the voices of the children in the film would reach lawmakers," she said.

Another person integral to this fight is Republican Senator Rob Portman from Ohio. He sponsored the SESTA bill. He said Backpage is more devious than you might think. They don’t just sit by and collect money. He said they work with pimps to create ads that won’t tip off cops the girl or boy is underage.

“When someone would send an ad in saying you know, cheerleader, or school girl, they would go to the person purchasing the ad and say you need to take that word out, but still place your ad with us - because they make money off of it? - because they make money off it," he said.

We reached out to Backpage. We emailed and called but did not hear back.

Fighting Backpage is nothing new. Founders Michael Lacey and Jim Larking, along with Backpage CEO Carl Ferrer, were arrested in California in 2016 for conspiracy to commit pimping and other charges. The case was dismissed two months later.

Lacey and Larkin issued a statement that said, in part, "As the federal courts have said time and again, there would be no internet if websites were liable for user content they neither created nor posted."

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Ambrose hopes the bill passes.

“That's why I came to DC, I came because they probably look at the news that same way I used to, as it just happens in other countries, but no this wasn't just like in my backyard, it came to my home. This ruined me," she said.

Like Pride, Ambrose said she'll never stop fighting.

“I’m gonna continue to fight, she's gone now, she doesn't have a voice, she can't fight anymore, as a mother, I'm gonna fight for her. I'm gonna fight every day until I take my last breath," she said.