For the first time Tuesday, the U.S. Supreme Court wrestled with the scope of a landmark federal law that's given sweeping legal immunity to internet and social media companies for more than 25 years.
Section 230 of the Communications Decency Act -- known in the tech world as the "26 words that created the modern internet" -- protects the companies from liability for content posted by individual users, no matter how discriminatory, defamatory or even dangerous the information may be.
The family of the only American killed in the 2015 Paris terror attacks, Nohemi Gonzalez, alleges that YouTube's parent company Google played a role in radicalizing the extremists that murdered their daughter by disseminating ISIS videos via algorithm. Lower courts have granted the internet giant immunity from the suit.
Oral arguments in the case, Gonzalez v. Google, stretched nearly three hours as the justices zeroed in on the concept of algorithms, which companies use to recommend third-party content, and whether they deserve protection as an inherent part of publishing information online, which is protected by Section 230.
"Algorithms are ubiquitous, but the question is what does the defendant do with algorithm," said Gonzalez family counsel Eric Schnapper. "If it uses the algorithm to direct, to encourage people to look at ISIS videos, that's within the scope of [liability]."
"It's the recommendation practice that we think is actionable," Schnapper said.
The company vigorously disagrees, insisting that its algorithms are content "neutral," taking cues from the interests of the user to organize and present relevant information, and that putting links, videos or tweets in some type of order is an inherent part of publishing in the online age.
"Helping users find the proverbial needle in the haystack is an existential necessity on the Internet," said Google attorney Lisa Blatt. "Search engines thus tailor what users see based on what's known about users."
Nearly all the justices appeared sympathetic to legal protection for internet companies as publishers, with many voicing concern about a potential flood of lawsuits that could come from ending immunity for algorithms.
"I don't know where you're drawing the line. That's the problem," Justice Samuel Alito said to the Gonzalez family attorney.
"What about users and retweets and likes?" asked Justice Amy Coney Barrett. "I gather [Section] 230 would protect me from liability if I simply retweeted."
"Those are difficult issues," replied Deputy U.S. Solicitor General Malcom Stewart speaking for the Biden administration, which supports lifting the liability shield for how websites organize and present content.
Justice Elena Kagan noted that algorithms are so integral to the digital age that allowing the Gonzalez family to sue over them could render Section 230 meaningless.
"We're a court. We really don't know about these things. You know, these are not like the nine greatest experts on the internet," Kagan said of her colleagues, eliciting a laugh from the courtroom gallery. "There's a lot of uncertainty going the way you would have us go, in part, just because of the difficulty of drawing lines in this area and just because of the fact that, once we go with you, all of a sudden we're finding that Google isn't protected. And maybe Congress should want that system, but isn't that something for Congress to do, not the court?"
Schnapper, the Gonzalez attorney, insisted that Congress never intended to shield algorithms from liability claims when it drafted the law in 1996.
"They're affirmatively recommending things. You turn on your computer and the computers at YouTube send you stuff you didn't ask them for. They just send you stuff. It's no different than if they were sending you e-mails," he said of how algorithms' recommendations work.
Blatt, the Google attorney, warned the court against opening the floodgates to liability lawsuits, saying it could lead to "death by a thousand cuts" for internet companies. It was a claim that appeared to resonate with several of the justices.
"What are the implications ... for the economy?" askedJustice Brett Kavanaugh. "We have to take seriously that, say, this is going to cause a lot of economic dislocation in the country."
"Lawsuits will be nonstop over defamatory material," he added.
Justice Ketanji Brown Jackson, while at times seeming sympathetic to limits on Section 230's protection, openly grappled with how algorithms differ from a newspaper editor deciding what stories go on the front page -- a legally protected decision.
"Why is calling it a recommendation actually any different?" she said to Schnapper.
"You have an algorithm, and in the universe of things that exist, you are presenting it to people so that they can read it," Jackson said. "Even though you call it a recommendation or whatever, why is that act any different than being a publisher?"
"With respect to what prominence you give it, that's the result of [an internet company's'] own choice, not the third-party poster [of the content]," Schnapper replied.
The Beatriz Gonzalez and Jose Hernandez, Nohemi's parents, spoke exclusively on-camera with ABC News ahead of the case, and were in attendance in the courtroom. "We feel confident after listening to all the arguments," Hernandez said after the hearing.
"We just hope that this, it’ll change the laws and it’ll be for the good," he said in an interview late last year. "So other families don't have the pain that we’re feeling."
A decision is expected by the end of June.