TikTok and its Chinese parent company ByteDance appeared before a federal appeals court on Monday, seeking to block a U.S. law that would ban the popular video-sharing app, arguing it violates free speech protections under the U.S. Constitution.

The law, set to take effect as early as January 19 next year, demands that ByteDance sell or divest TikTok's U.S. assets or face a nationwide ban. It was signed by President Joe Biden in April after getting clearance from Congress.

During a two-hour hearing before a three-judge panel of the U.S. Court of Appeals for the District of Columbia Circuit, Andrew Pincus, the attorney for TikTok and ByteDance, said the law is unprecedented and unfairly targets the app and its American users. He contended that the U.S. government has not provided sufficient evidence to prove that TikTok poses a national security threat, as claimed by the Justice Department.

Pincus emphasized that the law infringes on the First Amendment rights of TikTok and its 170 million American users by restricting their ability to freely express themselves on the platform.

"The law before this court is unprecedented, and its effect would be staggering," he told the judges. "For the first time in history, Congress has expressly targeted a specific U.S. speaker, banning its speech and the speech of millions of Americans."

Another attorney, representing content creators also contesting the law, said that it infringes upon the rights of U.S. speakers. He likened the law to a prohibition on Americans publishing content on other foreign-owned media platforms, like Politico, Al Jazeera or Spotify.

In their lawsuit filed in May, TikTok and ByteDance argued that the law violates the First Amendment by censoring a specific platform based on hypothetical future risks. They contended that upholding the statute would set a dangerous precedent, allowing Congress to bypass constitutional protections by citing national security concerns.

TikTok also highlighted that the law unfairly targets a single platform, describing it as an overreach that prevents Americans from "participating in a unique online community with more than 1 billion people worldwide."

(With input from agencies)