Backpage had drawn fierce opposition from some groups and scrutiny from lawmakers for the proliferation of child sex trafficking ads that appeared on the site, under code words like "Amber Alert".
The notice did not detail the reason for the seizure but noted that Justice Department's Child Exploitation and Obscenity Section, as well as the offices of the Texas attorney general and California attorney general, were involved.
"The Department of Justice's action against Backpage is good news for victims and survivors of online sex trafficking", Portman said.
On Friday an electronic sticker was slapped onto the online classified ad site, stating it has been seized by the Federal Bureau of Investigation, U.S. postal inspectors and the IRS. When Law&Crime reached out to the DOJ for confirmation, a spokesperson declined to comment, but did say that a news release is scheduled to be scheduled at that time.
"Today, Backpage was shutdown".
But those arguments were overwhelmed by stories from teenagers about being sold for sex on Backpage. The site's controversial adult section has often come under fire for allegations of prostitution and the sex trafficking of minors. The law has been scrutinized for its potential First Amendment infringements, though it has not yet been signed into law by President Donald Trump.
Last year, the creators of the website were charged with money laundering in California.
U.S. Senator Rob Portman (R-Ohio) praised the justice department for taking action against Backpage.com.
There would be "a dramatic shift in the marketplace starting tonight", he added. But until Friday the website had continued to operate, shielded by free speech protections.
Miss Marla moon, a sex worker who specializes in domination, told BuzzFeed News she lost $50 when Backpage went down Friday and that, for the past two years, she had spent $50 on Backpage ads almost every day.
The Supreme Court declined in January 2017 to consider a lawsuit by three young women who accused the site of facilitating their forced prostititution.
The site was largely a draw for its sex ads, and sex workers expressed dismay on Twitter about its closing.