The families of three victims of the Orlando, Florida, nightclub shooting massacre are suing Google, Facebook and Twitter for allegedly providing the Islamic State militant group (ISIS) with an infrastructure to conduct terrorist operations.

Related: Inside the worst mass shooting in U.S. history

The three families filed their civil lawsuit in a Michigan federal court on Monday, on behalf of victims Tevin Crosby, 25; Javier Jorge-Reyes, 40; and Juan Guerrero, 22. (Crosby was a native of Michigan, and Jorge-Reyes’s sister lives there.) Fox News first reported the case.

The men were among the 49 people killed when Omar Mateen opened fire at the Pulse nightclub on June 12, targeting the LGBT community. According to the FBI, it was the country’s worst mass shooting and its second-worst terrorist attack​.

Section 230 of the Communications Decency Act generally protects publishers from liability for information given by another provider. But Keith Altman, a partner at 1-800-Law-Firm who is representing the families, says the law doesn’t apply to the three tech giants because they act as information content providers by using algorithms to build user profiles and to select which advertisements to match with text for specific viewers.

“Defendants have incorporated ISIS postings along with advertisements matched to the viewer and ISIS postings to create new content for which Defendants have earned revenue,” the complaint alleges.

“When they do this, they actually create new content and the content is specifically designed,” Altman tells Newsweek. “So once they do that, they’re no longer just publishers. They’re no longer just passing through…. As far as I can tell, no one has ever argued this before.”

Jean Dasilva mourns for his deceased friend, Javier Jorge-Reyes, at a makeshift memorial for the victims of the nightclub shooting in Orlando, Florida, on June 14. Jorge-Reyes’s siblings are among the victims’ families who filed a civil lawsuit in federal court on Monday against Google, Facebook and Twitter, over…