Three women who said they were raped repeatedly after being sold for sex online can’t sue the site that hosted the ads because a “free and open Internet” outweighs the battle against sex trafficking, a federal judge has ruled.

“Congress has made the determination that the balance between suppression of trafficking and freedom of expression should be struck in favor of the latter in so far as the Internet is concerned,” wrote U.S. District Court Judge Richard Sterns.

Three women sued Backpage.com, which hosts classified ads that include escort services. The women said they were sold for sex as children — one said she “engaged in 10 to 12 sex transactions daily with adult men in Massachusetts,” according to Sterns’ order, issued last week.

Under the Communications Decency Act, websites like Backpage are protected, Sterns ruled. Backpage won a similar federal suit in Missouri in 2011.

“Putting aside the moral judgment that one might pass on Backpage’s business practices, this court has no choice but to adhere to the law that Congress has seen fit to enact,” Sterns wrote.

The women tried several approaches to get around federal law and one argued that photos posted of her on Backpage constituted copyright infringement. Sterns rejected the arguments, though he wrote, “To avoid any misunderstanding, let me make it clear that the court is not unsympathetic to the tragic plight described by Jane Doe No. 1, Jane Doe No. 2, and Jane Doe No. 3. Nor does it regard the sexual trafficking of children as anything other than an abhorrent evil.”

The women will appeal, according to their law firm, Ropes & Gray.

“This case presents a clash between two goals: the desire to support the development of the Internet and the critical need to curtail the online sexual exploitation of children,” the firm said in a statement. “We strongly disagree with the court’s conclusion that, where these goals conflict, the Internet always prevails under a federal statute that is intended to limit claims against Internet service providers.”

Backpage attorneys could not be reached for comment.