The US Supreme Court refused to save TikTok from a law requiring the popular short-video app to be sold by Chinese parent ByteDance or banned on Sunday in the US on national security grounds – a major blow to the platform used by nearly half of all Americans.

The justices ruled unanimously on Friday that the law, passed by a bipartisan supermajority in Congress last year and signed by Democratic President Joe Biden, does not violate the U.S. Constitution’s First Amendment protections against government curtailment of free speech. The justices affirmed the lower court’s decision upholding the measure after TikTok, ByteDance and some users of the app objected to it.

“There is no doubt that TikTok, for more than 170 million Americans, provides a distinctive and broad outlet for expression, a means of engagement, and a resource for community. But Congress has determined that divestment is necessary to address well-supported national security concerns regarding TikTok’s data collection practices and relationship with an adversary foreign.

“We conclude that the contested provisions do not violate the petitioners’ First Amendment rights,” the court added.

The Supreme Court acted quickly in the case, holding arguments on January 10, just nine days before the deadline set by law. This case pitted free speech rights against national security concerns in the age of social media.

A White House statement indicated that Biden would not take any action to rescue TikTok before the Sunday deadline set by law for divestiture.

White House press secretary Karine Jean-Pierre, in a statement, reiterated Biden’s position that “TikTok should remain available to Americans, but simply under U.S. ownership or other ownership that addresses the national security concerns Congress identified in developing this law.”

Jean-Pierre added that given the timing, taking the necessary measures to implement the law “should fall to the next administration.”

Trump’s team did not immediately respond to requests for comment, but in an interview with CNN, Trump said the decision about TikTok’s future would be up to him, but did not provide any details about what steps he would take.

“It’s up to me in the end, so you’ll see what I do,” Trump said. “Congress has given me the decision, so I will make the decision.”

TikTok is one of the most prominent social media platforms in the United States, and is used by about 170 million Americans – nearly half of the country’s population, including many young people. TikTok’s powerful algorithm, its main asset, feeds individual users with short videos tailored to their liking.

China and the United States are economic and geopolitical rivals, and Chinese ownership of TikTok has for years raised concerns among American leaders. The TikTok battle erupted during the final days of Biden’s presidency — as Republican Donald Trump succeeds him on Monday — and at a time of escalating trade tensions between the world’s two largest economies.

‘Serious threat’

During arguments in the case, Justice Department lawyer Elizabeth Prelogar said that the Chinese government’s control of TikTok poses a “serious threat” to US national security, as China seeks to collect massive amounts of sensitive data on Americans and engage in covert influence operations. Prelogar said China is forcing companies like ByteDance to secretly hand over data on social media users and implement Chinese government directives.

Prelogar added that TikTok’s massive data set represents a powerful tool that the Chinese government can use for harassment, recruitment, and espionage, and that China “could weaponize TikTok at any time to harm the United States.”

The law was passed last April. The Biden administration defended it in court. TikTok and ByteDance, as well as some users who post content on the app, challenged the measure and appealed to the Supreme Court after losing on December 6 to the US Court of Appeals for the District of Columbia Circuit.

Trump’s opposition to the ban represents a reversal in his stance from his first term in office when he aimed to ban TikTok. Trump said he has a “warm spot in my heart for TikTok,” arguing that the app helped him attract young voters in the 2024 election.

In December, Trump asked the Supreme Court to suspend the law to give his next administration “the opportunity to pursue a political resolution of the issues in the case.” But while Trump vowed to “save” TikTok, many of his Republican allies supported the ban.

Mike Waltz, Trump’s incoming national security adviser, said Thursday that the new administration would keep TikTok alive in the United States if there was a workable agreement. Waltz said the incoming administration “will put measures in place to prevent TikTok from going dark,” and cited a provision in the law that allows for a 90-day extension if there is “significant progress” toward divestiture.

Senate Democratic Leader Chuck Schumer said Thursday that TikTok should be given more time to find an American buyer, and that he would work with the Trump administration “to keep TikTok alive while protecting our national security.”

TikTok CEO Shou Zi Chew will attend Trump’s inauguration on Monday, sitting among other high-profile invitees.

TikTok said the law jeopardizes the First Amendment rights of not only itself and its users, but also of all Americans. TikTok said the ban would hurt its user base, advertisers, content creators and employee talent. TikTok has 7,000 US employees.

Without a decision from Biden to formally invoke a 90-day delay in the deadline, companies that provide services for TikTok or host the app could face legal liability. It is not immediately clear whether TikTok’s business partners, including Google, Apple and Oracle, will continue doing business with it before Trump’s inauguration.

Noel Francisco, a lawyer for TikTok and ByteDance, told the Supreme Court that the app is “one of the most popular expression platforms in America” and said the law would require it to “go dark” unless ByteDance carries out a qualified divestment.

TikTok plans to shut down the app’s US operations on Sunday except for a last-minute reprieve.

Francisco said the US government’s real goal with this law was to express — specifically, the fear that Americans could be “persuaded by Chinese disinformation.” The First Amendment leaves that to the people of the United States, not the government, Francisco said.