Judges on the U.S. Court of Appeals for the D.C. Circuit on Monday questioned whether national security concerns justify speech restrictions as they weighed a First Amendment challenge to a federal law forcing TikTok to either be sold or shut down in the United States.

The Protecting Americans from Foreign Adversary Controlled Applications Act requires TikTok’s China-based parent company ByteDance to either sell the social media platform within 270 days or be banned in the United States. TikTok argues the law unlawfully restricts its content curation and that lawmakers’ worries about foreign manipulation of content on the app and data security don’t justify limiting the platform’s speech.