TikTok, an online video entertainment platform, and its Chinese parent company ByteDance on Tuesday filed a legal challenge against the U.S. government over a law forcing ByteDance to sell off the ultra-popular app or face a nationwide ban in the country.

U.S. President Joe Biden signed a TikTok ban bill into law last month after it was passed by both houses of U.S. Congress.

"Congress has taken the unprecedented step of expressly singling out and banning TikTok: a vibrant online forum for protected speech and expression used by 170 million Americans to create, share, and view videos over the Internet," said TikTok in the petition filed in the Court of Appeals for the District of Columbia Circuit.

"For the first time in history, Congress has enacted a law that subjects a single, named speech platform to a permanent, nationwide ban, and bars every American from participating in a unique online community with more than 1 billion people worldwide," the company added. 

TikTok pointed out in the petition that the law – the Protecting Americans From Foreign Adversary Controlled Applications Act – is unconstitutional.

"Banning TikTok is so obviously unconstitutional, in fact, that even the Act's sponsors recognized that reality, and therefore have tried mightily to depict the law not as a ban at all, but merely a regulation of TikTok's ownership," said TikTok.

The law only gives ByteDance 270 days to sell TikTok to a non-Chinese buyer, with the possibility of a 90-day extension if the U.S. president determines it is necessary.

"But in reality, there is no choice," said TikTok, noting that the "qualified divestiture" demanded by the Act to allow TikTok to continue operating in the United States is simply not possible: not commercially, not technologically, not legally.

The TikTok ban, citing unfounded national security concerns due to its Chinese ownership, has drawn widespread criticism from various quarters, both within and outside the United States, with people questioning the motivations behind Washington's suppression of the popular app, and raising concerns about constitutional rights and the principle of fair competition being violated. 

Opposition voices on TikTok ban 

The U.S. crackdown on TikTok, which damages investors' confidence in the international investment environment and undermines the normal global economic and trade order, will eventually backfire on the U.S., said Chinese Foreign Ministry spokesperson Wang Wenbin in March. 

Wang made the remarks at a regular press briefing when asked to comment on the U.S. lawmakers' voting on a possible TikTok ban. "In recent years, although the U.S. has never found evidence of TikTok threatening its national security, the country has never stopped suppressing TikTok."

"Such bullying practice, which fails to prevail in fair competition, disrupts normal business activities of enterprises, damages investors' confidence in the international investment environment and undermines the normal global economic and trade order," said Wang, adding that this approach will ultimately backfire on the U.S. itself.

SpaceX CEO Elon Musk also expressed his support for the former U.S. President Donald Trump in denouncing a potential ban on TikTok, which enjoys widespread popularity among U.S. youth. 

The billionaire argued in March that a possible TikTok ban in the U.S. could limit access to the app, which he said amounts to "censorship and government control," and Donald Trump, who once attempted to remove TikTok from U.S. app stores, said that a TikTok ban could benefit Facebook, censuring it as "an enemy of the people." 

In April, Musk once again voiced his opposition to a proposed U.S. ban on competitor TikTok, citing violation of freedom of speech.

"TikTok should not be banned in the U.S., even though such a ban may benefit the X platform," Musk said in a post on the social network he acquired in 2022.

"Doing so would be contrary to freedom of speech and expression."

It would also give the U.S. president the authority to designate other applications as a threat to national security if they are controlled by a country considered hostile.

(With input from agencies)