A classified ad website that has been accused of facilitating child sex trafficking sued Washington state on Monday, asking the court to block a new law that requires companies to verify the ages of people in sex-related advertisements.

Under the law, which goes into effect Thursday, classified advertising company representatives who publish third-party, sex-related ads can be prosecuted for peddling children. It was designed to target backpage.com, which hosts 70 percent of online prostitution ads in the United States, according to the Associated Press. Five U.S. senators and 51 state attorneys general have publicly condemned the website for promoting child sex trafficking.

In a complaint filed in U.S. District Court in Seattle, backpage.com agues the law infringes on First Amendment rights and conflicts with the federal Communications Decency Act, which says online service providers are not responsible for the content of third-party ads.

"This means that every service provider — no matter where headquartered or operated — must review each and every piece of third-party content posted on or through its service to determine whether it is an 'implicit' ad for a commercial sex act in Washington, and whether it includes a depiction of a person, and, if so, must obtain and maintain a record of the person's ID," the complaint reads. "These obligations would bring the practice of hosting third-party content to a grinding halt."

Because the law doesn't require knowledge of wrongdoing, it could make hundreds of websites such as Facebook and Google criminally liable for content they may not even be aware of, Elizabeth McDougall, general counsel of Village Voice Media Holdings, which owns Backpage.com, told law.com.

“The trafficking of children for sex is an abomination,” McDougall said.

But she doesn't see Washington's law as the answer.

“I believe aggressive improvements in technology and close collaboration between the online service community, law enforcement and NGOs (non-governmental organizations) is the best approach to fighting human trafficking,” she said.

While child advocates would like to see the "adult services" section of backpage.com shut down completely, they have praised Washington's law as a "step in the right direction."

Other states, including Connecticut, are already considering similar legislation. In New Jersey last week, state Sen. Christopher "Kip" Bateman submitted a copycat bill that would make it a third-degree felony to publish a commercial sex advertisement depicting a minor, njtoday.net reported.

“It is utterly incomprehensible to abuse children in sex advertisements and to publish those ads for a buck,” Bateman said. “What is just as deplorable is that this abuse-for-profit also directly promotes the crimes of human sex trafficking and prostitution involving minors.”