The Biden administration’s new law forcing the sale or ban of TikTok is the unconstitutional result of “political demagoguery” and should be overturned, TikTok attorneys said in a court brief Thursday marking the start of one of the most consequential legal battles in American internet history.

The briefs, filed by TikTok and a group of eight creators, largely reprise past arguments that a law demanding TikTok’s China-based owner, ByteDance, sell its U.S. operations by Jan. 19 or face a nationwide ban would violate Americans’ First Amendment right to free expression.

“Never before has Congress silenced so much speech in a single act,” TikTok’s brief said. The law “sets a dangerous precedent allowing the political branches to target a disfavored speech platform and force it to sell or be shut down.”

But TikTok also went on offense, sharing for the first time internal documents from years of failed negotiations with the federal government that it says show the administration was not operating in good faith.

The company included a roughly 100-page draft national security agreement it offered to the government in August 2022 in hopes of resolving its concerns – a proposal that would have given federal officials extraordinary power to shape and oversee TikTok’s U.S. operation, including a nationwide kill switch the government could deploy if they believed the app remained a threat.

The Biden administration declined the offer, arguing that it was insufficient to neutralize their concerns but without detailing why. In First Amendment cases, judges have traditionally called for the government to pursue its goals with the “least restrictive” impact on Americans’ speech.

The high-profile Washington brawl could have a dramatic impact on the future of online speech. Upholding the law could decimate an online cornerstone for news and entertainment used by 170 million nationwide. But overturning it would rebuke a largely bipartisan act of Congress and undercut one of its few substantial pieces of tech legislation in decades.

The administration has said the law is critical to protect national security, citing fears that the Chinese government could boost propaganda through the popular app’s video recommendations or spy on Americans’ personal lives – neither of which it has shown evidence of occurring. The Justice Department is expected to officially respond to TikTok’s brief next month.

But TikTok argued in its brief that the law would turn the U.S. app into an “island” where American users would be walled off from videos created outside their national borders and have an “experience detached from the rest of the global internet” – an echo of the splintered and suppressive Chinese internet laws that American lawmakers have long criticized.

A group of TikTok creators also filed a legal challenge last month, with funding from TikTok; the cases have since been consolidated. In a legal brief Thursday, the creators – a cookie baker in Memphis, a skin-care entrepreneur in Atlanta, a football coach in North Dakota – said the law would be a “devastating blow” to their online communities and livelihoods.

Topher Townsend, an Air Force veteran and conservative rapper in Mississippi, said the law “betrays the values that I sought to protect.” Brian Firebaugh, a Texas rancher who posts under @cattleguy, added, “If you ban TikTok, you ban my way of life.”

TikTok’s proposal had followed years of negotiations with the Committee on Foreign Investment in the United States, a multiagency federal group known as CFIUS that reviews business deals for national security risks. The company has said the group abruptly ended talks without a clear explanation. (An administration official said last month that the company was told a forced sale was the only path forward.)

TikTok also gave the court a last-ditch letter ByteDance attorneys had sent in April to a Justice Department official pleading for the talks to resume. In the 13-page letter, the attorneys said the government had offered only “vague and inchoate responses” to the company’s concerns and seemed glued to a position that was “unmoored from reality.”

While the company had stayed silent to protect the negotiation’s confidentiality agreements, the attorneys argued, it had been repeatedly undercut by “problematic and damaging” comments from administration officials and leaks to the media.

“The Company has approached this process responsibly and constructively in the face of … an extraordinary public campaign against it, increasingly led by the very officials in the U.S. government” involved in the negotiations, the attorneys wrote. “We fear … that CFIUS has become compromised by political demagoguery.”

In its brief, TikTok attacked the government’s reliance on “speculative” worries and Congress’ “collection of ‘cans,’ ‘coulds,’ ‘mights,’ and ‘potentials’” in the deliberations that preceded the law’s passage.

“Congress reached for a sledgehammer without even considering if a scalpel would suffice,” the brief said.

The law, the brief added, suffered from a “fatal” constitutional flaw: It singles out TikTok by name while affording other “foreign adversary controlled applications” a process for review, which TikTok called a “unique, two-tiered system of speech regulation.”

“Congress itself laid down a generally applicable standard and process” and denied TikTok “alone the protections … for no reason it saw fit to share,” the brief said. “That is a powerful indication that punishing [TikTok] was the point.”

In its brief, TikTok argues that a sale would be financially and technically impossible within the government’s one-year deadline and would basically guarantee a ban. Past ban attempts by the Trump administration and the state of Montana have been thrown out of court as government overreaches.

The TikTok app runs on roughly 2 billion lines of code written and maintained by more than 4,000 software engineers, the company has said; a new buyer would largely need to start from scratch. And any sale would likely be blocked by the Chinese government, which added recommendation algorithms – TikTok’s backbone – to its export-control list after the failed Trump ban order in 2020.

Severing TikTok’s U.S. app from the ByteDance engineers in China who built it and the global sales, marketing and creator-relations teams who maintain it would dismantle its operations into a “shell of its former self,” the brief argued. It would also put the company at an unfair disadvantage to U.S.-based companies, such as Meta and Microsoft, which employ technical personnel in China.

In a declaration filed alongside the brief, TikTok’s head of operations, Adam Presser, sought to drive home the value of Americans’ connection to the rest of the world. U.S. users posted more than 5 billion videos last year, he said, and half of the 13 trillion views they received came from foreign viewers. A quarter of the videos those Americans watched came from outside the country, too.

Doubts over TikTok’s U.S. survival had already damaged the company, Presser said, adding that “competitors have been aggressively trying to recruit our talent” since the law was passed.

The briefs kick off a fast-tracked schedule ordered last month by a panel of judges at the U.S. Court of Appeals for the D.C. Circuit. Both TikTok and the Justice Department asked the court to offer a ruling by Dec. 6, so as to allow for a possible Supreme Court review before the law takes effect. Oral arguments are slated to begin Sept. 16 – just four months before the Jan. 19 divestment deadline.

Because the sale-or-ban law set the appeals court as the “exclusive jurisdiction” for any challenge, the brief offers TikTok one of its only chances to defend itself in court. Unlike in district court, where a fact-finding process involves submitting evidence and calling witnesses, the appeals judges review legal briefs and weigh in on constitutional arguments, and the only way to overturn their ruling is through the Supreme Court.

Alongside its brief, TikTok filed hundreds of pages of supporting documents, including declarations from TikTok-retained experts who argued on the company’s behalf.

Christopher Simkins, a former CFIUS negotiator and DOJ investigator, said TikTok’s proposal was “the most sophisticated and thorough mitigation agreement” he had seen in decades of reviewing similar contracts.

Randal Milch, a New York University law professor, outlined the complexities of past tech-company transactions to argue that the law was effectively a ban because a forced-sale option on the government’s timeline was “entirely illusory.”

And Steven Weber, a professor at the University of California at Berkeley, said the government’s concerns about propaganda, disinformation and data security were “industry-wide issues that are not unique to TikTok.”

The data TikTok collects is “not meaningfully different” from what’s gathered by Google, Facebook and Snapchat, he said, and many U.S. tech companies have China-based subsidiaries that “therefore face the same theoretical risk.”

“There is no evident national security rationale for the Act’s particular focus on TikTok,” he wrote. “It is arbitrary to select one market participant for policy issues that an entire industry faces.”