The justices are expected to rule quickly in the case, which pits national security concerns about China against the First Amendment’s protection of free speech.

Lawyers for TikTok will argue that banning the app will violate the free speech of 170 million American users. The Justice Department will contend that the app is a national security risk.

TikTok threatened to shut down the popular platform in America on Jan. 19 unless the Supreme Court strikes down or otherwise delays the effective date of a law aimed at forcing TikTok’s sale by its Chinese parent company.