WASHINGTON — The Supreme Court heard arguments on Wednesday over whether internet platforms may be sued for aiding and abetting international terrorism by failing to remove videos supporting the Islamic State.
The case, which concerns a federal law allowing suits for “knowingly providing substantial assistance” to terrorists, was linked to one argued Tuesday that considered the separate question of whether platforms are immune from lawsuits under a 1996 law that shields them from liability for what their users post.
As a practical matter, the court’s ruling in Wednesday’s case, Twitter v. Taamneh, No. 21-1496, could effectively resolve both cases and allow the justices to duck difficult questions about the scope of the 1996 law, Section 230 of the Communications Decency Act.
The argument on Wednesday was technical. The justices teased apart elements of the law before them, the Justice Against Sponsors of Terrorism Act, parsing its provisions and posing hypothetical questions about what sort of conduct it covered. Chief Justice John G. Roberts Jr. said that “the discussion this morning has really taken on a very academic tone.”
The case concerned Nawras Alassaf, who was killed in a terrorist attack at a nightclub in Istanbul in 2017 for which the Islamic State claimed responsibility. His family sued Twitter and other tech companies, saying they had allowed ISIS to use their platforms to recruit and train terrorists.
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Seth P. Waxman, a lawyer for Twitter, stressed that the plaintiffs had not accused his client of providing “substantial assistance, much less knowing substantial assistance, to that attack or, for that matter, to any other attack,” adding that it was undisputed that Twitter “had no intent to aid ISIS’s terrorist activities.”
He went on: “What we have here is an alleged failure to do more to ferret out violations of a clear and enforced policy against assisting or allowing any postings supporting terrorist organizations or activities.” That was not enough, Mr. Waxman argued, to amount to “aiding and abetting an act of international terrorism.”
Justice Sonia Sotomayor told Mr. Waxman that the fact remained that “you knew that ISIS was using your platform.”
Justice Brett M. Kavanaugh summarized Twitter’s position: “When there’s a legitimate business that provides services on a widely available basis in an arm’s length manner, it’s not going to be liable under this statute even if it knows bad people use its services for bad things.”
Justice Elena Kagan asked Edwin S. Kneedler, a lawyer for the federal government arguing in support of Twitter, how the case before the court differed from ones concerning providing banking services to known terrorists.
“They provide a hundred other clients who are not terrorists with the same banking services, but they provide this known terrorist with these banking services that are very important to its terrorist activities,” she said. “Can you go after that person under this statute?”
Mr. Kneedler said yes, so long as the customer was “somebody who is a leader or somebody who you know has committed or is about to commit a terrorist act.”
Justice Kagan said that banking and social media may not be so different.
“We’re used to thinking about banks as providing very important services to terrorists,” she said. “Maybe we’re not so used to, but it seems to be true that various kinds of social media platforms also provide very important services to terrorists.”
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Eric Schnapper, a lawyer for the plaintiffs, acknowledged that their lawsuit did not accuse Twitter of complicity in the Istanbul attack. Their lawsuit, he said, was focused on Twitter’s role in “recruiting and fund-raising.”
“Of the overall cost of running a terrorist organization, the cost of a particular attack is a very small part,” he said. “Running terrorist organizations is very expensive. It involves fund-raising. There are lots of salaries. There’s travel. There’s bribery. There’s forging documents.”
He added: “That’s why it’s so important that the court hold that the entire enterprise being aided matters. If you limit the aid that matters to the tip of the spear, you’ve written out of the statute almost all the assistance that matters.”
At Tuesday’s argument, Justice Amy Coney Barrett suggested that a decision in favor of Twitter in Wednesday’s case could effectively resolve both disputes and spare the court from having to rule on the scope of Section 230 in a suit against Google.
“If you lose tomorrow,” she asked Mr. Schnapper on Tuesday, “do we even have to reach the Section 230 question here?”
Mr. Schnapper was not ready to make that concession, indicating that his clients would try to amend their complaint in their case against Google if the court ruled for Twitter in Wednesday’s case.
