Family members of a man killed in an attack in Istanbul are urging a federal appellate court to reinstate a lawsuit accusing Twitter, Google and Facebook of assisting ISIS.

“For years, Twitter, Google, and Facebook … have allowed ISIS to utilize their services to carry out terrorist activities, including recruiting, radicalizing, and instructing terrorists, as well as raising funds and inciting fear among civilian populations,” family members of Nawras Alassaf, a Jordanian citizen who was killed in the January 1, 2017 Reina nightclub shooting, argue in papers filed last week with the 9th Circuit Court of Appeals. “By furnishing these platforms to ISIS, defendants allow the terrorist group to virtually recruit operatives as well as publicize the success of their operations.”

Alassaf’s family alleged in a complaint filed in 2017 that the killer, Abdulkadir Masharipov, was radicalized by social media.

Last year, U.S. District Court Judge Edward Chen’s dismissed the lawsuit at an early stage. Chen ruled that the family’s complaint didn’t spell out how the platforms could have caused the attack.

Plaintiffs do not allege that Mr. Masharipov ever saw any specific content on social media related to ISIS. Nor are there even any factual allegations that Mr. Masharipov maintained a Facebook, YouTube, and/or Twitter account,” Chen wrote.

He added that complaint also alleged that Masharipov trained with al-Qaeda in 2011 — suggesting that he could have been radicalized through other sources

The family members now argue they should have been allowed to proceed with claims that the tech companies “substantially assisted ISIS.”

“They provided ISIS with the infrastructure to ‘virtually’ radicalize prospective recruits and encourage them to commit acts of terrorism throughout the world,” the family says in its new court papers. “Without Defendants’ social media platforms ISIS would practically have no means of radicalizing prospective recruits beyond ISIS’s territorial borders and encouraging them to commit acts of terrorism.”

All three companies have prevailed in similar battles in trial courts and in at least two appellate courts. Most recently, earlier this month the 6th Circuit Court of Appeals rejected an attempt to revive a lawsuit that sought to hold Google, Twitter and Facebook responsible for the mass shooting by Omar Mateen at the Pulse nightclub in Orlando, Florida.