A worried and wary Supreme Court heard arguments on Tuesday in a case that could revolutionize the architecture of the internet and social media companies. At issue in the case is a 1996 law that shields internet platforms from being sued for material that appears on their sites.

On one side of the case is the family of an American student killed in a terrorist attack in Paris. Her family claims that YouTube, owned by Google, aided and abetted in the attack by recommending ISIS videos to people who might be interested in them. The argument is that by recommending these videos Google promoted ISIS recruiting, propaganda and terrorist attacks.

Joining Google on the other side are other multi-billion dollar companies, indeed some of the most valuable companies in the world—from Facebook and Twitter to many smaller companies as well—all of which together represent a huge portion of the U.S. economy.

With the stakes in the case so high, the justices seemed both cautious and skeptical of some of the arguments made by each side, with no clear liberal-conservative ideological divide.

'Not ... the nine greatest experts on the internet'

Justice Elena Kagan seemed to sum up the countervailing winds when discussing how the EU deals with these issues, including levying a huge fine against Google. But, she noted, that fine was not levied by a court.

"I think that's my concern," Kagan said. "I can imagine a world where none of this stuff gets protection ...Why is it that the tech industry gets a pass?" But on the other hand, she stressed, "We're a court. We really don't know about these things."

Gesturing to her colleagues on the bench, Kagan added, "You know, these are not like the nine greatest experts on the internet," a comment followed by laughter in the courtroom.

That said, the justices tried their best, repeatedly trying to find a line between what is permissible for internet providers to do in organizing content on their platforms.

Justice Clarence Thomas asked whether algorithms are the same across the board for cooking, racing or ISIS videos.

Lawyer Eric Schnapper, representing the family of Nohemi Gonzalez, the young woman killed in Paris, said the algorithms are the same, but when it comes to ISIS videos, the result is that companies are encouraging illegal conduct covered by the Federal Antiterrorism Act—a law that bars material aid to terrorist groups.

And yet, observed Justice Thomas, the algorithm is the same. "if you're interested in cooking," he said, "you don't want thumbnails on light jazz."

Drawing a line between an algorithm and collusion

Chief Justice John Roberts pointed to an analogy made by Google. If a bookseller "has a table with sports books on it," and somebody is looking for a book about Roger Maris, and the bookseller says, "Well, it's over there on the table with the other sports books," isn't that analogous to what's happening here? asked Roberts.

Lawyer Schnapper said "no," arguing there is, in fact, a difference.

"What's happening in YouTube is they're not doing that," he said. "I type in ISIS video and they're sending me to a catalogue of thumbnails which they created."

The justices didn't seem to see a clear line.

"How do I draw a line between an algorithm and active collusion?" Justice Sonia Sotomayor asked.

Justice Amy Coney Barrett questioned Twitter's liability for a retweet of a link to a terrorist video. And Justice Neil Gorsuch asked whether artificial intelligence should be treated differently than algorithms because it is actual content that is being created and provided by the platform. Justice Brett Kavanaugh worried about the consequences of any broad decision in the case. It could, he said, "crash the digital economy," and "lawsuits will be nonstop."

Defending Google, lawyer Lisa Blatt agreed. She argued that the 1996 federal law at issue in this case was aimed at shielding internet platforms from lawsuits.

"The basic features of topic headings, up next, trending now . . . we would say are core, inherent," she said. "They're no different than expressing what is implicit in any publishing."

But Chief Justice Roberts was skeptical, contending, "It seems to me that the language of the statute doesn't go that far."

Blatt replied that there are 3.5 billion searches per day, all displays of other people's information, and if the court were to prevent aggregating and curating those searches for users, that would be very different from what Congress envisioned when it provided platforms with immunity.

While the justices indicated that it might be better for Congress to take on the task of modifying the 1996 law, at the same time, several fired some pointed shots across the bow, hinting at limited patience with internet platform providers. Indeed, while today's case could well end in a fizzle, more cases are expected next term.