The U.S. Supreme Court on Monday boosted one of the tech industry's go-to defenses in suits to hold websites liable for content posted by others, rebuffing an appeal by women who accused an online ad site of promoting child sex trafficking. The high court let stand a lower court's decision last year to dismiss the lawsuit because the Communications Decency Act, a 1996 law protecting free speech on the internet, shielded Backpage from liability for the content of the ads. Tech companies commonly invoke the Communications Decency Act in defending against similar lawsuits.