The U.S. Supreme Court ruled on Friday that the federal government can legally shut down TikTok in the U.S., delivering a stunning blow to the viral video app used by about half of Americans.

Last April, President Biden signed a bipartisan bill that said TikTok must spin off from its China-based parent company, or shut down in the U.S.

TikTok contested the ban in court, arguing that it violates the free speech rights of both users and the company — an appeal that it took all the way to the Supreme Court, which heard the case on Jan. 10.

The high court's decision means that starting on Jan. 19, tech giants Apple and Google can no longer offer TikTok on their app stores. Web-hosting providers must cut ties with the platform or be subject to fines of $5,000 for each user that can still access the service, a penalty that can easily add up to billions of dollars.

TikTok's seemingly nonstop legal limbo has sown widespread confusion among users over when and if the app will indeed stop working one day. But now, the country's highest court has affirmed the federal ban.

"There is no doubt that, for more than 170 million Americans, TikTok offers a distinctive and expansive outlet for expression, means of engagement, and source of community. But Congress has determined that divestiture is necessary to address its well-supported national security concerns regarding TikTok's data collection practices and relationship with a foreign adversary," the court wrote in an unsigned opinion. "We conclude that the challenged provisions do not violate petitioners' First Amendment rights."

The justices acknowledged the tight time frame they were operating under, emphasizing that the ruling should be seen as applying only to TikTok, not as a sweeping precedent. "That caution is heightened in these cases, given the expedited time allowed for our consideration. Our analysis must be understood to be narrowly focused in light of these circumstances," the justices wrote.

Anupam Chander, a law professor at Georgetown University who has followed the TikTok case closely, said the justices did indeed frame the ruling as TikTok-specific, but it could have implications that exceed the app's corporate ownership.

"There is a Bush v. Gore aspect to the decision in that it's a one-off and not meant to have greater precedential value," said Chander, referring to the landmark 2000 ruling. "But this will be a very important decision," he said. "And it gives enormous power to Congress to act on data privacy questions."

The ruling follows an emergency hearing held last week in which justices appeared skeptical that the free speech rights of millions of American TikTok users should surpass the national security risk Congress says China poses. Lawmakers fear the Chinese government could use the app to spy on Americans or disseminate pro-China propaganda, even though TikTok skeptics have never shown concrete examples of that happening.

When Congress passed the law in April taking aim at TikTok, lawmakers provided a way for the company to avoid expulsion: Fully divest from China-based parent company ByteDance, which would resolve the national security concerns of lawmakers and the intelligence community in Washington.

But to TikTok executives, that is merely a symbolic life raft, since ByteDance has consistently indicated that the platform, China's first global social media hit, is not for sale. Furthermore, export control laws in China prevent TikTok's algorithm from being sold unless Beijing regulators bless the transaction, something China experts have said the country is not likely to do.

The only justice to voice concern about the free speech implications of a ban was Neil Gorsuch, who called banning TikTok to remove the China threat a "paternalistic point of view."

"I mean, don't we normally assume that the best remedy for problematic speech is counter speech?" said Gorsuch, adding that TikTok has raised the possibility of including a disclaimer on its app indicating that some content could be covertly manipulated by China.

U.S. Solicitor General Elizabeth Prelogar, representing the federal government, quickly shot that down with this analogy: "Imagine if you walked into a store and I had a sign that said one of 1 million products in this store causes cancer," she told the court. "That is not going to put you on notice about what product is actually jeopardizing your health."

On Friday following the Supreme Court's ruling, Biden White House press secretary Karine Jean-Pierre said in a statement that it would be up to the incoming administration to implement the law. "Given the sheer fact of timing, this administration recognizes that actions to implement the law simply must fall to the next administration, which takes office on Monday," she said.