US Supreme Court lets Twitter off hook in terrorism lawsuit over Istanbul massacre

Relatives of Jordanian man killed in 2017 attack accused social media platform of aiding and abetting ISIS

Floral tributes and Turkish flags outside the Reina nightclub in Istanbul, which was the site of a 2017 terror attack. AP

The US Supreme Court on Thursday refused to clear a path for victims of attacks by militant organisations to hold social media companies liable for failing to prevent the groups from using their platforms, handing a victory to Twitter.

The justices, in a unanimous decision, reversed a lower court's ruling that had revived a lawsuit against Twitter by the American relatives of Nawras Alassaf, a Jordanian man killed in a 2017 ISIS attack during a New Year's celebration in an Istanbul nightclub.

The Istanbul massacre on January 1, 2017, killed Mr Alassaf and 38 others.

His relatives accused Twitter of aiding and abetting ISIS, which claimed responsibility for the attack, by failing to police the platform for the group's accounts or posts in breach of a federal law called the Antiterrorism Act, which enables Americans to recover damages related to “an act of international terrorism”.

Twitter and its backers had said that allowing lawsuits such as this would threaten internet companies with liability for providing widely available services to billions of users because some of them may be members of militant groups, even as the platforms regularly enforce policies against terrorism-related content.

The case hinged on whether the family's claims sufficiently proved that the company knowingly provided “substantial assistance” to an “act of international terrorism” that would allow the relatives to maintain their suit and seek damages under the antiterrorism law.

After a judge dismissed the lawsuit, the San Francisco-based 9th US Circuit Court of Appeals in 2021 allowed it to proceed, concluding that Twitter had refused to take “meaningful steps” to prevent ISIS's use of the platform.

President Joe Biden's administration supported Twitter, saying the Antiterrorism Act imposes liability for assisting a terrorist act and not for “providing generalised aid to a foreign terrorist organisation” with no causal link to the act at issue.

Google and Meta's Facebook, also defendants, did not formally join Twitter's appeal.

ISIS called the Istanbul attack revenge for Turkish military involvement in Syria. The main suspect, Abdulkadir Masharipov, an Uzbek citizen, was later captured by police.

Twitter in court papers has said that it has terminated more than 1.7 million accounts for violating rules against “threatening or promoting terrorism”.