The law that could ban TikTok is coming before the Supreme Court on Friday, with the justices largely holding the app’s fate in their hands.

The popular social media platform says the law violates the First Amendment and should be struck down.

TikTok’s parent company is based in China, and the U.S. government says that means it is a potential national security threat. Chinese authorities could force it to hand over sensitive data on the huge number of Americans who use it or could influence the spread of information on the platform, they say.

An appeals court has upheld the law, which bans TikTok unless it’s sold.

The law is set to take effect Jan. 19, the day before a new term begins for President-elect Donald Trump, who has 14.7 million followers on the platform. The Republican says he wants to “save TikTok.”

The short-form video-sharing app could be shut down in less than two weeks if the Supreme Court upholds the law.

Congress passed the measure with bipartisan support, and President Joe Biden, a Democrat, signed it into law in April.

TikTok’s lawyers challenged the law in court, joined by users and content creators who say a ban would upend their livelihoods. TikTok says the national security concerns are based on inaccurate and hypothetical information.

But a unanimous appeals court panel made up of judges appointed by both Republican and Democratic presidents has upheld the law.

The justices will issue a decision after arguments Friday, a lightning-fast movement by court standards.

The conservative-majority court could drop clues about how it’s leaning during oral arguments.

TikTok lawyers have urged the justices to step in before the law takes effect, saying even a monthlong shutdown would cause the app to lose about one-third of its daily American users and significant advertising revenue.

The court could quickly block the law from going into effect before issuing a final ruling, if at least five of the nine justices think it is unconstitutional.