Twitter, Facebook and Google are asking a court to refuse to revive a lawsuit accusing them of helping to spread terrorist propaganda.
The companies argue that a trial judge correctly ruled that they didn't cause the shooting, and that the Communications Decency Act generally protects tech platforms from civil lawsuits based on crimes committed by users.
"This suit was not brought against anyone involved in committing the attack," the companies write in papers filed Wednesday with the 9th Circuit Court of Appeals. "Instead, Plaintiffs brought the action against Twitter, Google, and Facebook -- operators of global Internet platforms that are used by people across the world to send and share hundreds of millions of messages, Tweets, videos, and other posts on myriad topics."
The lawsuit stems from a shooting in July 2016, when Micah Johnson killed five police officers in Dallas. Rick Zamarripa, the father of one of the officers who was killed, and Demetrick Pennie, a police officer who responded to the shooting and subsequently suffered emotional distress, sued Twitter, Facebook and Google.
Zamarripa and Pennie alleged that the terrorist group Hamas spread propaganda on the tech companies' platforms, and that Johnson was "radicalized" partly as a result of that material.
U.S. Magistrate Judge Joseph Spero in the Northern District of California dismissed the case last December.
Zamarripa and Pennie appealed that decision in June. They argue that the lawsuit should be reinstated for several reasons, including that it should have been under the "Justice Against Sponsors of Terrorism Act" -- a federal law that enables people to bring civil suits against anyone who provides "material support" to terrorists. They argue that the anti-terrorism law creates an exception to the Communications Decency Act's immunity provisions.
Twitter, Facebook and Google dispute that interpretation. They argue that Congress didn't indicate any intention to override the Communications Decency Act's protections when enacting the Justice Against Sponsors of Terrorism Act.
Earlier this year, the 9th Circuit sided with Twitter in a similar dispute. In that matter, family members of two people killed in a terrorist shooting -- Lloyd “Carl” Fields, Jr. and James Damon Creach -- sued Twitter for allegedly supporting ISIS by allowing members to create accounts on the service. The appellate judges ruled that the family members couldn't proceed because they didn't show that Twitter directly caused the shooting.