A group of TikTok users has sued the state of Montana in a bid to overturn its plan to ban the app from January 1, 2024.

The complaint was filed on Wednesday evening in the U.S. District Court for the District of Montana just hours after Montana Governor Greg Gianforte (R) signed into law a bill banning the Chinese-owned app over concerns it could impact U.S. national security.

In documents filed with the court, the group of five TikTok users said: “Montana has no authority to enact laws advancing what it believes should be the United States’ foreign policy or its national security interests, nor may Montana ban an entire forum for communication-based on its perceptions that some speech shared through that forum, though protected by the First Amendment, is dangerous.”

It added: “Montana can no more ban its residents from viewing or posting to TikTok than it could ban the Wall Street Journal because of who owns it or the ideas it publishes.”

U.S. authorities have long expressed concerns that TikTok’s Beijing-based owner, ByteDance, may be interfered with by the Chinese government and therefore see the app as a national security risk. A former ByteDance executive recently claimed that the Chinese Community Party “maintained supreme access” to TikTok data stored in the U.S. when he worked for the company between 2017 and 2018. Others claim the Chinese authorities could even influence the app’s algorithm to serve up pro-China content. TikTok has always denied any wrongdoing.

While more than half of U.S. states have already banned TikTok from federal devices, Montana this week became the first to introduce a law banning it statewide. Fines will be handed out to companies like Apple, Google, and TikTok if they enable downloads of the app in the state, though individuals who continue to use TikTok will not be punished. It remains to be seen if other states will take similar action to Montana, and whether more TikTok users will come forward and sue the state in a bid to block the controversial ban.

TikTok is a hugely popular app, with the company claiming to have 150 million users in the U.S. and more than a billion globally. But with many lawmakers from across the political divide piling pressure on the app and its maker, TikTok’s future in the U.S. is far from clear.