The Supreme Court on Tuesday debated the scope of a 27-year-old federal law that shields social-media companies from liability for content published by others. At issue in Gonzalez v. Google is whether Section 230 of the Communications Decency Act protects internet platforms when their algorithms target users and recommend someone else’s content. Google and its supporters warned in legal briefs that a ruling against them could massively reshape legal liability for tech companies across the county, but after nearly three hours of argument on Tuesday, the justices appeared wary of taking such a significant step.

The case was filed by the family of Nohemi Gonzalez, a 23-year-old American woman who was studying in Paris when she was killed in an ISIS attack there in 2015. Their lawsuit alleges that Google, which owns YouTube, violated the Antiterrorism Act’s ban on aiding and abetting terrorism by (among other things) recommending ISIS videos to users through its algorithms, thereby aiding ISIS’s recruitment.