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The families of three victims of a 2015 terrorist attack in San Bernardino, California have launched a lawsuit against tech giants Google, Twitter, and Facebook.

The lawsuit, which has been filed in California, claims that the three companies have permitted the Islamic State group to develop an online presence, and provided space for the militant group to propagate their beliefs through social media.

The families of the victims say that IS propaganda provided central motivation to the perpetrators of the San Bernardino attack by Syed Rizwan Farook and his wife Tashfeen Malik.

Some 14 people were killed, and 22 more seriously injured when Farook and Malik targeted a local Department of Public Health training event and a Christmas party on 2 December 2015.

"Even if Farook and Malik had never been directly in contact with IS, IS' use of social media directly influenced their actions on the day of the San Bernardino massacre," the filed lawsuit reads.

Speaking on the case Keith Altman, one of the attorneys representing the families, said that IS and other terrorist organisations "rely upon social media in order to recruit, in order to conduct terrorist operations.

"It is not really in dispute that this is what takes place."

Measures, such as the Communications Decency Act, state that companies operating social media platforms are not liable for content posted online by their users.

In legal cases targeting social media platforms for online content posted by users, tech companies regularly express sympathy, deny liability, and invoke immunity through legal precedents.

In recent years, since the emergence of the Islamic State group, critics have called on tech giants, and in particular social media platforms such as Facebook and Twitter, to establish better measures to prevent the propagation of terrorist content on their websites.

In one controversial case last year, a number of media organisations reported that while IS propaganda could be found on Facebook, members of the militant group also appeared to be attempting to sell sex slaves through the social media platform.

In order to combat this online threat, and in addition to a disturbing phenomenon of people live-streaming suicide attempts online, Facebook recently announced that it is set to hire 3,000 people around the world to monitor video content and posts uploaded to the popular website for violent or criminal acts.

This follows an announcement last year in which Facebook said it was teaming with Twitter, YouTube, and Microsoft in order to create a database of digital "fingerprints" designed to identify violent terrorist imagery or recruitment videos.