Video-sharing app TikTok and a group of its users faced a skeptical federal appeals court during oral arguments Monday in a bid to overturn a law that would mandate the company’s U.S. subsidiary be sold or face a ban, as a panel of judges focused on the company’s China-based ownership.

Attorneys for the social media giant and content creators urged the U.S. Court of Appeals for the District of Columbia Circuit to find that the law would infringe on the free speech rights of the platform and its users. But the three judges on the panel spent much of Monday’s two-hour arguments focused on Congress’ designation of China as an “adversary” of the United States and the company’s ties to its China-based parent company, ByteDance.

All three judges raised concerns about the risks of limiting congressional ability to regulate what a foreign adversary or enemy in war could own in the United States. Judge Neomi Rao said that, even if it did impact what TikTok or its users could say online, the law “is also regulating foreign ownership, which is a separate, non-expressive interest of the federal government.”

Members of Congress and the Biden administration have argued that the Chinese government could force ByteDance to provide access to the reams of data it has about TikTok users or allow manipulation of content on the application in ways that compromise U.S. interests.

“There is so much happening in China outside the United States that it poses a grave national security risk,” Justice Department attorney Daniel Tenny said Monday.

‘Remarkable determination’

An attorney for TikTok, Andrew Pincus, argued that other laws concerning foreign ownership, like those prohibiting ownership of nuclear waste sites, had nothing to do with free speech. Pincus argued that the law was “unprecedented” and upholding the law would bring about “staggering” changes to free speech and give Congress vast powers to ban speech from foreign entities in the United States.

“Congress didn’t do any of the things that the First Amendment requires,” such as considering lesser measures such as disclosure about possible manipulation of the content, Pincus said.

Rao pushed back on that, saying it would be a “quite a remarkable determination to make for this court” that Congress would have to pursue disclosure rather than a sale.

Pincus argued that the federal government cannot get away with restricting a company’s speech simply because it is owned by a foreign corporation. He pointed to foreign ownership of companies like Politico and Spotify, said that a sale of the American subsidiary is not possible and added that the law amounts to a ban of speech the government doesn’t like.

Judge Sri Srinivasan pushed Pincus on whether that test would limit Congress’ ability to ban ownership of a company by an enemy country or the spread of propaganda during wartime.

Pincus argued that the federal government has in the past turned to less extreme measures than a forced sale or a ban. Pincus also pointed out that the fact of a war is different from the federal government’s unproven fears about content manipulation.

“The government solution to propaganda in every other context has been disclosure, not a ban,” Pincus said.

The case comes at the confluence of years of concerns by lawmakers over foreign influence of U.S. politics and court fights over free speech online.

The law, passed by Congress earlier this year, mandates that TikTok’s American subsidiary be divested from China-based ownership or be blocked in the United States. TikTok says it is “technologically, commercially, and legally infeasible” to divest the U.S. operations.

The Biden administration has argued in the case that intrusion into the company’s ownership is justified because of the security risks of potential Chinese government use of the platform’s trove of data and access to Americans’ cellphones.

‘First Amendment alarm bells’

The China-based ownership of TikTok emerged as a key issue during the arguments. At one point, Srinivasan said the government may be in a different position if the case didn’t involve foreign ownership of TikTok. He pointed to a Supreme Court case earlier this year concerning state laws in Texas and Florida that sought to regulate social media companies’ content moderation.

“Once you put an interest in play that is called ‘content manipulation,’ that sets off First Amendment alarm bells when you don’t have foreign control,” Srinivasan said.

Tenny argued that the manipulation the government was concerned about would come from actions by ByteDance employees in China, where there would be no free speech protections like in the United States. Pincus disputed that, arguing that TikTok’s U.S. subsidiary makes its own choices about how content is moderated on the application.

Jeffrey Fisher, attorney for the app’s content creators, argued that the law effectively targets the free speech of users in the United States by keeping them from working with the publisher of their choice: TikTok.

“When you have speech in the United States, our history and tradition is we do not suppress that speech because we don’t like those ideas,” Fisher said.

Fisher said a less intrusive alternative, such as the surgeon general warnings on cigarette cartons, would not violate the First Amendment rights of users.

The law at issue specified that challenges be brought at the D.C. Circuit rather than a trial court, and the panel does not face a deadline to issue a ruling. The unusual nature of the challenge came up several times during arguments, as both Pincus and Tenny disputed the facts of TikTok U.S.’s relationship with ByteDance.

Rao said it was “strange framework” for the court to review Congress’ actions as it normally does for administrative agencies.