A potential nationwide TikTok ban could dramatically reshape social media for millions of content creators and users.

The court is hearing oral arguments on TikTok’s bid to block a law that would lead to its ban in the U.S. starting Jan. 19 if it isn’t sold by its Chinese owner.

A majority of the justices appeared more concerned about the national security implications of the popular app’s Chinese ownership than about the restrictions on free speech the law would impose.