TikTok filed a lawsuit Monday to stop Montana from banning the popular video app, stepping up its efforts to stop a ban that would be the first of its kind in the nation.

In a demand filed in the US District Court for the District of Montana, the company said the Montana law violated the First Amendment and parts of the US Constitution that limit state powers. The ban was to “unconstitutionally close the speech forum for all speakers on the app,” the company said in the lawsuit.

TikTok sued days after Montana Gov. Greg Gianforte signed the ban, which would fine the app if it operated in the state or fine app stores if they allowed it to be downloaded, signing it into law.

The state law has become a test case to determine whether it is possible to ban the use of TikTok, which is owned by Chinese internet company ByteDance, on national security grounds. The ban, which goes into effect Jan. 1, has already raised questions about how it would apply within Montana’s borders.

“We are challenging Montana’s unconstitutional ban on TikTok to protect our business and the hundreds of thousands of TikTok users in Montana,” Brooke Oberwetter, a spokeswoman for TikTok, said in a statement. “We believe our legal challenge will prevail based on an extremely strong set of precedents and facts.”

Emily Flower, a spokeswoman for Montana Attorney General Austin Knudsen, said, “We expected legal challenges and are fully prepared to defend the law that helps protect the privacy and security of Montanans.”

The lawsuit adds to those legal challenges. A group of TikTok users filed a separate lawsuit challenging the Montana bill on Wednesday, the day Gianforte signed it, saying it violated their First Amendment rights and exceeded the state’s legal authority. The law has also sparked an outcry from civil liberty and digital rights groups, including the American Civil Liberties Union and Columbia University’s Knight First Amendment Institute.

TikTok, which has more than 150 million users in the US, has been in limbo under two presidential administrations as it worked to calm concerns about its Chinese ownership. The company, which has been waiting for the Biden administration to approve its plan to operate in the United States, has already faced bans from government devices in more than two dozen states, as well as from universities and the military.

The Montana ban was written by Mr. Knudsen, a Republican, and introduced by a Republican state senator this year. State lawmakers said the ban would prevent the Chinese government from accessing Montanans’ personal information. The ban debate began shortly after a Chinese spy balloon floated over the state, drawing national attention.

The new law will prevent TikTok from operating the app in the state. App store operators such as Apple and Google will also be prohibited from making them available for download in the state. TikTok, Apple and Google could face daily fines of $10,000 if they don’t comply.

In its lawsuit, TikTok said Montana lacked the legal authority to impose a ban because it would regulate interstate commerce, which is the purview of the federal government. The ban also violates a constitutional prohibition on legislation that targets an individual or specific groups for punishment, the lawsuit argued.

“TikTok’s ban singles out the TikTok app for this punishment, even though the data allegedly collected by the app is no different than data collected from any number of other sources and is widely available on the data broker marketplace. the company said. said in his complaint.

Critics of the ban believe it will be difficult to enforce even if the courts don’t block it. TikTok users in Montana could still use the app if they disguised their location using virtual private network software, while Montanans living in border cities can get Internet access through cell phone towers in other states. TechNet, a lobbying group representing Apple and Google, has said it’s impossible for app stores to restrict downloads to a single state.

Mr Knudsen’s office said last week that TikTok could enforce the ban with technology the online gambling industry already uses to block access to an app from a state where it is illegal.

Litigation over the ban could take months to resolve. Because the ban would not go into effect until next year, there is no immediate need for the courts to stop it from going into effect.

TikTok and its supporters have managed to use the courts to stop a previous ban in the United States. In 2020, TikTok sued the federal government when President Donald J. Trump used his emergency economic powers to issue an executive order to block the app from operating in the United States. One judge sided with the company, and another judge blocked the ban after a challenge from a group of creators.

TikTok has been banned in some countries, including India in 2020. Britain, Canada, and France recently banned the app on official government devices.