The fate of TikTok — and its 170 million American users — hangs in the balance, as the Supreme Court considers the constitutionality of a law that would ban the platform in the U.S. if its China-based owner, ByteDance, doesn’t sell off its U.S. operation by Jan. 19.

If the court upholds the law — as a lower court did last month — TikTok’s days in the country would be numbered.

“On January 19th, as I understand it, we shut down,” TikTok lawyer Noel Francisco told justices during oral arguments on Friday.

This doesn’t mean that the viral video app will automatically disappear from people’s phones or that individuals will risk punishment just for logging in.