The father of a young woman killed in the Paris massacre last November is suing Google, Facebook and Twitter, claiming that the companies provided "material support" to extremists in violation of the law.
Reynaldo Gonzalez, whose daughter Nohemi was among 130 people killed in the Paris attacks, filed the suit on Tuesday in the US District Court in the Northern District of California.
The suit claims the companies "knowingly permitted" the Islamic State group, referred to in the complaint as "ISIS", to recruit members, raise money and spread "extremist propaganda" via their social-media services.
The Gonzalez suit is very similar to a case brought against Twitter in January by the widow of a contractor killed in an attack in Jordan. It includes numerous identical passages and screenshots, although the lawyers in the cases are different.
In statements, Facebook and Twitter said on Wednesday the Gonzalez lawsuit is without merit, and all three companies cited their policies against extremist material.
Twitter, for instance, said that it has "teams around the world actively investigating reports of rule violations, identifying violating conduct, and working with law enforcement entities when appropriate".
Facebook's statement read, in part, that if the company sees "evidence of a threat of imminent harm or a terror attack, we reach out to law enforcement".
Google, meanwhile, said it won't comment on pending litigation, but noted that that it has "clear policies prohibiting terrorist recruitment and content intending to incite violence and quickly remove videos violating these policies when flagged by our users".
Under US law, internet companies are generally exempt from liability for the material users post on their networks.
But it isn't clear if that legal defence will suffice in this case. Ari Kresch, a lawyer with 1-800-LAW-FIRM who is part of the Gonzalez legal team, said in an email that the lawsuit targets social media companies because of the behaviour they enabled, not what they published.
"This complaint is not about what ISIS's messages say," he wrote. "It is about Google, Twitter, and Facebook allowing ISIS to use their social media networks for recruitment and operations."
The Gonzales complaint also alleges that Google's YouTube shared revenue with IS from ads that ran with its videos.
Benjamin Wittes, a senior fellow at the Brookings Institution, agrees that the legal "safe harbour" might not shelter social-media companies in such cases.
Twitter may not succeed in quashing the similar lawsuit filed in January on those grounds, Wittes argues. But he said Twitter could still prevail because the causal link between its alleged support for extremists and the attack is very weak.
