The Supreme Court said Monday it won't hear an appeal from three sex trafficking victims who accuse advertising website Backpage.com of helping to promote the exploitation of children.

The justices left in place a lower court ruling that said federal law shields Backpage from liability because the site is just hosting content created by people who use it.

The women say they were sold as prostitutes in Massachusetts and Rhode Island through advertisements for escort services on the site when they were as young as 15. They say Backpage is not protected by the Communications Decency Act because the company not only hosted the ads, but created a marketplace that makes child sex trafficking easier. Backpage has denied those allegations.