Big Law attorneys representing TikTok and creators on the platform urged a federal appeals court Thursday to strike down a law that could lead to the app being shut down in the United States, saying the statute violates the First Amendment right to free speech.

The law, 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 face a ban in the United States. In passing the bipartisan bill, lawmakers cited concerns about national security posed by TikTok.