The US Supreme Court ruled Thursday that Twitter is not liable under the Antiterrorism and Effective Death Penalty Act when users post terrorism-related content. Rather than addressing §230 of the Communications Decency Act, which many believed would determine the case, the court decided that the plaintiffs in Twitter v. Taamneh failed to state a claim upon which the court could grant relief. The court then used the same reasoning in a related case, Gonzalez v. Google LLC, to find that Google is also not liable.

Justice Clarence Thomas delivered the unanimous opinion of the court. Thomas centered his opinion around the plaintiff’s claim that Twitter, Facebook and Google aided and abetted ISIS in committing the Reina nightclub attack in Istanbul, Turkey. Under 18 USC § 2333(d)(2), US nationals who are victims of terrorist attacks may hold any individual found to have aided and abetted in the terrorist attack civilly liable. The court found that, based upon that statute, the plaintiffs failed to prove that any of the social media platforms aided and abetted in ISIS’s attack on the Reina nightclub.

The case arose after ISIS took responsibility for the attack that killed 39 people and injured 69 more. The family of Nawras Alassaf, one of the deceased, brought suit against Facebook, Twitter and Google. They claimed the technology giants knew of ISIS’s use of the platforms to recruit members and spread propaganda. The plaintiffs also alleged that the companies had the ability to flag, report and remove terrorist accounts but failed to do so.

In Twitter, the court established a three-prong test to address whether or not someone “aided and abetted” a terrorist under §2333(d)(2). That test is as follows:

1. There was a terrorist attack committed by a terrorist;
2. Defendants knew they played some sort of role in that terrorist’s enterprise; and
3. Defendants gave “such knowing and substantial assistance” to the terrorist that they “culpably participated” in the terrorist attack.

The court found that, undoubtedly, the first two prongs were met in Twitter. However, the plaintiffs fell short of proving the third prong. The court viewed the social media platform’s recommendation algorithms, which formed the basis of Taamneh’s claims, as “merely part of” the platforms’ infrastructures. The court held that the algorithms, on their own, were not enough to meet the threshold required to meet the third prong. The court said that using such a standard would be too broad. The opinion reads:

To be sure, it might be that bad actors like ISIS are able to use platforms like defendants’ for illegal–and sometimes terrible–ends. But the same could be said of cell phones, email, or the internet generally. Yet, we generally do not think that…[these] providers incur culpability merely for providing their services to the public writ large.

To do so, the court said, would be to hold “defendants liable as having aided and abetted each and every ISIS terrorist act committed anywhere in the world.” For that reason, the court reversed the lower court’s ruling, finding that the social media platforms cannot, in this case, be held liable under §2333(d)(2).

Using the same reasoning as they did in Twitter, the court in Gonzalez found that the plaintiffs failed to prove that Google, as the owner and operator of YouTube, had any agreement that would meet the threshold for conspiracy liability with ISIS to post the contested content on YouTube. The court then remanded the case back down to the lower court to reconsider the case under the new Twitter standard.