TikTok’s US future hangs in the balance in court

A three-judge panel of the U.S. Court of Appeals for the District of Columbia Circuit is hearing arguments in a showdown over the future of the popular social-media app.

A law signed by President Biden this spring requires TikTok’s parent company, Beijing-based ByteDance, to sell the platform by Jan. 19 with a possible 90-day extension. The law doesn’t make it a crime to use TikTok, but it does prohibit mobile app stores from letting users download or update it.

The sell-or-ban law gained bipartisan support after lawmakers received warnings from the intelligence community about China’s ability to exploit the app used by some 170 million Americans, roughly half of the population.

The U.S. government says China’s potential ability to use TikTok to wage information warfare and spy on Americans represents a national-security threat. And it argues that divestiture from Chinese ownership is the only assurance of defusing the danger.

ByteDance has said it can’t and won’t sell its U.S. operations by the deadline. The Chinese government has also signaled that it won’t allow a forced sale of TikTok to go through.

TikTok and several of its star content creators have claimed in lawsuits that the U.S. government crackdown on TikTok is based on speculative and secret security concerns in violation of the First Amendment.

“Never before has Congress silenced so much speech in a single act," TikTok’s lawyers stated in a brief urging the panel to block the law.

The short-form video platform, which has operated as TikTok in the U.S. since 2018, quickly gained mass appeal as an entertainment platform, news source, cultural tastemaker and activist hub.

The U.S. government says TikTok creators can post what they want, just not on a major platform controlled by a foreign adversary.

“The statute is aimed at national-security concerns unique to TikTok’s connection to a hostile foreign power, not at any suppression of protected speech," Justice Department lawyers said in a brief.

Monday’s argument could offer clues about where the panel might be leaning or how the First Amendment’s protections should be weighed—if at all—against national-security concerns.

But the hearing before Circuit Judges Sri Srinivasan, Neomi Rao and Douglas Ginsburg will offer a limited window into the facts of the case.

Much of the government’s evidence is classified and shielded not just from the public but from TikTok’s lawyers, a point of frustration for the petitioners’ legal teams. TikTok has asked the court to appoint a special master who could make recommendations to the court about the handling of classified information in the case.

“In this case we don’t know a lot of the underlying facts," said University of Minnesota national security law professor Alan Rozenshtein, who has written on the case.

The government has stated that TikTok and the other petitioners “have no due process, statutory or regulatory right to access" the secret materials, whose exposure it argues would cause “grave damage" to national security.

But TikTok says the constitutional stakes should curb the secrecy. In an August filing, its lawyers said the U.S. government hasn’t shown them any evidence that China has manipulated the content that Americans see on TikTok or that China has accessed U.S. user data.

The Justice Department has told the court that it is “prepared to argue this case publicly" without discussing the classified content. The court has the option of holding a closed-door session with U.S. government attorneys to discuss the secret evidence.

The U.S. government has shown the judges statements from senior intelligence officials about the dangers posed by TikTok and a transcript of a classified House committee hearing from March that fueled the legislation’s passage. Publicly viewable portions of the filings intimate that the government’s national-security concerns are more than hypothetical.

“Intelligence reporting further demonstrates that ByteDance and TikTok Global have taken action in response to PRC [People’s Republic of China] demands to censor content outside of China," Casey Blackburn, a senior U.S. intelligence official, wrote in a heavily redacted filing.

TikTok’s parent company, he wrote in a passage surrounded by blacked-out text, has a “demonstrated history of manipulating the content on their platforms, including at the direction of the PRC."

TikTok says it has spent $2 billion walling off U.S. user data on Oracle-owned U.S.-based servers—measures that the U.S. government says fail to adequately insulate TikTok from Chinese influence or prevent user data from being accessed by ByteDance employees located in China.

The U.S. has long restricted foreign ownership of radio and television broadcasting. But the “Protecting Americans from Foreign Adversary Controlled Applications Act," the name of the TikTok law, marked the first time Congress took such drastic actions against a major internet platform.

TikTok and other challengers have cited a 1965 Supreme Court case in which the high court struck down a law that required citizens to register their names with the U.S. Postal Service to receive Communist propaganda.

The U.S. government says the TikTok law isn’t restricting the Chinese government’s views on the internet but targeting China’s control over the platform.

TikTok content creators who sued—a group of eight that includes “Cattle Guy" Brian Firebaugh—say the law against the platform is a prior restraint on speech, likening the divestiture demands to the Vietnam War-era suppression of the leaked Pentagon Papers that the Supreme Court rejected.

“The government could no more prohibit a freelance journalist from publishing in a magazine of her choice; forbid an actor from working with a particular director; or tell a musician what studio he can record in," lawyers for the content makers stated in a brief.

The litigants have asked the D.C. Circuit to rule by Dec. 6 so there is enough time for a Supreme Court review before the law takes effect.

Write to Jacob Gershman at jacob.gershman@wsj.com