Soon after Biden signed the bill to ban TikTok in April, the company and a consortium of its users retaliated by filing lawsuits accusing the federal government of violating their First Amendment rights. In December, a federal appeals court upheld the ban law, leaving TikTok with only one legal pathway left to save itself: An appeal to the Supreme Court.

Many of these same arguments were made at Friday’s hearing. Justice Brett Kavanaugh called the government’s data security rationale “strong.” Justices Elena Kagan and Neil Gorsuch called into question the government’s assertion that app could host “covert” Chinese manipulation operations, arguing that TikTok’s algorithm was just as opaque as those belonging to other social media companies.

"We all now know that China is behind it," Kagan said.

Fisher, who represents the creators involved in the case, argued that the justices did not have to answer questions related to security which would be better resolved by broader data privacy legislation.

“If Congress, in this very law, regulated data security in other ways with the data brokers that's perfectly permissible,” Fisher told the court. “But the question before you today was narrower. The question is, is this law before you sustainable on security grounds? And that answer has to be no," Fisher told the court.

Justices expressed some doubt as to whether the law actually limits TikTok’s freedom of expression, given the option to divest. “TikTok can continue to operate on its own algorithm on its own terms, as long as it's not associated with ByteDance,” Justice Ketanji Brown Jackson said.

If the ban goes into effect, Apple and Google would be required to remove TikTok from the US versions of their app stores, preventing any new downloads from happening in the country. Internet hosting and data storage providers will also be forbidden from offering their services to the company. Users with TikTok already downloaded onto their devices may still continue to have access, at least for a short period of time after the ban goes into effect. Once removed from app stores, users won’t be able to download updates to TikTok and the app could be...