• by Wendy Davis  @wendyndavis, June 1, 2018

Victims of a mass shooting in Dallas are asking a federal appellate court to revive a lawsuit alleging that Twitter, Facebook and Google enabled the spread of terrorist propaganda.

The suit stems from a 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, ruling that Zamarripa and Pennie hadn't shown that the tech companies did anything to cause the shooting. He also ruled that the Communications Decency Act immunized the tech companies from most of the claims. That law generally provides that web companies can't be sued in civil court for crimes committed by users.

Zamarripa and Pennie on Thursday asked the 9th Circuit Court of Appeals to reinstate the lawsuit. Among other arguments, they say Spero shouldn't have dismissed the case without allowing them to beef up their allegations and re-file them. They also contend that their suit should have been allowed 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.

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.