TikTok’s fate now rests in the hands of the Supreme Court, which grappled Friday with whether the company’s ties to a foreign adversary are so deep that national security concerns outweigh the company’s and its users’ First Amendment free speech rights.

The company has asked the justices to step in and block a law passed last year by Congress, which will force ByteDance, the Chinese parent company, to divest TikTok by Jan. 19. Otherwise the social media app will disappear from U.S. platforms.

TikTok and some of its users have challenged the law, saying it tramples on their First Amendment rights to associate and speak freely.

“This case ultimately boils down to speech. What we’re talking about is ideas,” said Noel Francisco, TikTok’s lawyer. “If the First Amendment means anything, it means the government cannot restrict speech in order to protect us from speech.”

But Solicitor General Elizabeth Prelogar, arguing for the government, said the law’s goal isn’t to shut down the platform, and officials would be happy to see TikTok survive.

The problem, she said, is that TikTok is currently too tied to the People’s Republic of China, a nefarious adversary that could use the platform to undermine U.S. national security.She said secret documents provided to the court make clear what those national security concerns are.

“Congress just wants to cut the PRC out of the equation altogether,” she said.

Ms. Prelogar also insisted there’s no First Amendment rights for a foreign corporation.

The justices seemed conflicted in their questions to the lawyers, wondering whose speech rights are at stake, and whether the government’s stated national security interests were enough to overcome those rights.

“Congress doesn’t care about what’s on TikTok,” Chief Justice John G. Roberts Jr. said. “They’re not saying TikTok has to stop. They’re saying the Chinese government has to stop controlling TikTok. So it’s not a direct burden on the expression at all. Congress is fine with the expression. They’re not fine with a foreign adversary, as it is, gathering information.”

TikTok is a U.S.-based company, but its major social media app uses computer source code from ByteDance, including the algorithm that decides which content to promote.

Congress, in passing the law, concluded that the Chinese government regularly orders its companies to cooperate with Beijing. That means the algorithm could promote pro-Chinese propaganda. Lawmakers also worry that Beijing is harvesting Americans’ data through the app and could use it for nefarious anti-American purposes.

Mr. Francisco said TikTok has independent decision-making powers and could change the algorithm — but it would be difficult, and the company doesn’t want to. Forcing that is a violation of its speech rights, the lawyer said.

“The fact is, TikTok as a U.S. company does have a choice over the algorithm,” Mr. Francisco said. “What they clearly have the authority to do is shut down the platform in the face of Chinese pressure.”

Congress approved the legislation last April with strong bipartisan support, and President Biden signed it into law.

It gave ByteDance 270 days to sell the company or else U.S.-based tech services would be ordered to stop offering or supporting the app. If they fail to do so they could face civil penalties.

TikTok says roughly 170 million Americans use the short-video sharing platform and that 17% of Americans get their news from TikTok.

TikTok lost in a lower court, and the justices refused to issue an injunction before they heard from other parties.

President-elect Donald Trump has urged the high court to delay implementing the law to give him time during his new administration to strike a deal that would not compromise national security or the First Amendment.

Although his petition is not on behalf of either party, he has been vocal in his defense of TikTok — a reversal from his previous critical stance of the app.

Mr. Trump has more than 14 million followers on the popular social media platform and has credited it with helping him win support among young voters.

Mr. Francisco said even if the app goes dark on Jan. 19, Mr. Trump could suspend the ban once he’s in office, which could restore operations. Jeffrey Fisher, the lawyer for TikTok users, disputed that.

Mr. Fisher said “it’s a very weird law” if the government was concerned about data security because it targets foreign ownership on the basis of a specific viewpoint or perspective.

He said that violates the First Amendment rights of Americans using the platform that could soon go dark.

Ms. Prelogar said she thinks there’s a game of chicken going on with ByteDance trying to bully the U.S. into retreating on the divestiture demand, but she said once the deadline is passed she thinks the company will become interested in the divestiture.

The cases are TikTok v. Garland and Firebaugh v. Garland. Brian Firebaugh is a TikTok content creator.

• Stephen Dinan can be reached at sdinan@washingtontimes.com.

• Alex Swoyer can be reached at aswoyer@washingtontimes.com.