The Supreme Court appears poised to uphold a law that bans TikTok in the US over national security concerns unless its China-based parent company sells the platform ahead of a 19 January deadline.

The Court’s nine justices heard from lawyers representing TikTok, and content creators that the ban would be a violation of free speech protections for the platform’s more than 170 million users in the US.

The US government argued that without a sale, TikTok could be used by China as a tool for spying and political manipulation.

A decision by the top court has to be made within days. President-elect Donald Trump – who returns to the White House in just over a week – now argues against the ban.

The law requires TikTok’s parent company ByteDance to sell it in the US or cease operations on 19 January. The company has said it will not sell the short-form video platform.

Congress passed the law with support from both the Democratic and Republican parties – a moment that marked the culmination of years of concern about the widely popular platform, which is known for its viral videos and traction among young people.

The legislation does not forbid use of the app, but would require tech giants such as Apple and Google to stop offering it and inhibit updates, which analysts suggest would kill it over time.

TikTok has repeatedly denied any potential influence by the Chinese Communist Party and has said the law violates the First Amendment free speech rights of its users.

Noel Francisco, a former US solicitor general appearing for the platform, stressed the ban on the most popular speech platform for Americans could also open the door to a dangerous form of censorship.

He argued that “the government cannot restrict speech in order to protect us from speech”.

“That’s precisely what this law does from beginning to end.”

A representative for platform creators argued they should be free to use the publisher of their choice.

Jeffrey L Fisher, a Stanford University law professor representing creators who sued over the law, told the court on Friday that the country has historically faced “ideological campaigns by foreign adversaries”.

But he said that under the First Amendment, mere ideas do not represent a national security threat.

Justice department lawyer Elizabeth B Prelogar told the court that ByteDance’s ties to the Chinese government made it a national security risk.

She told the court that Beijing “could weaponise TikTok at any time to harm the United States”.

During nearly three hours of arguments, the nine justices returned time and again to the national security concerns that gave rise to the law in the first place, while also probing free speech questions.

“Are we supposed to ignore the fact that the ultimate parent is, in fact, subject to doing intelligence work for the Chinese government?” conservative Chief Justice John Roberts asked TikTok lawyer Mr Francisco.

Justice Brett Kavanaugh drilled into concerns the US government has raised about the data the app collects on its users and how that data might be used.

The risks seem like a “huge concern for the future of the country”, he said.

In December, US President-elect Donald Trump urged the court to delay its decision until he returns to the White House to enable him to seek a “political solution” to resolve the issues at hand.

TikTok’s lawyer told the court on Friday that, as he saw it, the platform would “go dark” on 19 January without intervention.

Ms Prelogar, arguing for the US justice department, said “nothing permanent” had to happen on that day and there was still time for a sale.

Forcing the app to go dark could be just the “jolt” ByteDance needs to seriously consider a sale, she said.

“It will fundamentally change the landscape with respect to what ByteDance might consider,” she said, comparing the situation to “game of chicken” and one in which the US should not “blink first”.

After the hearing, legal observers predicted that the Supreme Court’s justices appeared to be swayed by the government’s concerns.

“Traditionally the Supreme Court has been willing to defer somewhat when national security is at stake,” said University of Richmond law professor Carl Tobias.

“I expect that the justices by a majority will side with the government,” he added.

Jacob Hubert, a lawyer and the president of the Liberty Justice Center – which represents BASED Politics, an internet content creator – said it was still difficult to predict how the court would rule.

But he says the ban would violate the freedom of speech of millions of Americans – a point he believes was effectively made by TikTok’s lawyers.

“It’s not about China’s rights, or the Communist Party’s rights,” he said. “It is about the rights of Americans who use TikTok to, largely, speak with other Americans.”

More than a hundred people braved freezing conditions in Washington DC to attend the hearing in person.

Chloe Joy Sexton – one of the TikTok creators named in the suit – said that the platform brought many creators “financial independence”, including many mothers.

“A TikTok ban would place these women, myself included, in true financial jeopardy,” she told reporters. “It would destroy both my business and the community that means so much to me.”

Danielle Ballesteros, a student at UC San Diego, said had been waiting outside the court since 06:30 local time.

“I feel like TikTok doesn’t deserve to be banned,” she told BBC News.

While admitting to using it “probably too much”, she said she believes the app to be an important news source for her generation.

TikTok is already banned from government devices in many countries, including in the UK. It faces more complete bans in some countries, including India.

Last December, a three-judge appeals court decision upheld the law, noting China’s record of acting through private companies and saying the measure was justified as “part of a broader effort to counter a well-substantiated national security threat posed” by the country.