The two sides in the momentous clash at the Supreme Court over a measure that could shut down TikTok made their closing written arguments on Friday, sharply disputing China’s influence over the site and the role the First Amendment should play in evaluating the law.
Their briefs, filed on an exceptionally abbreviated schedule set last month by the justices, were part of a high-stakes showdown over the government’s insistence that ByteDance, TikTok’s parent company, sell the app’s operations in the United States or shut it down. The Supreme Court, in an effort to resolve the case before the law’s Jan. 19 deadline, will hear arguments at a special session next Friday.
The court’s ruling, which could come this month, will decide the fate of a powerful and pervasive cultural phenomenon that uses a sophisticated algorithm to feed a personalized array of short videos to users. TikTok has become, particularly for younger generations, a leading source of information and entertainment.
“Rarely if ever has the court confronted a free-speech case that matters to so many people,” a brief filed Friday on behalf of a group of TikTok users said. “170 million Americans use TikTok on a regular basis to communicate, entertain themselves, and follow news and current events. If the government prevails here, users in America will lose access to the platform’s billions of videos.”
The briefs made only glancing or indirect references to President-elect Donald J. Trump’s unusual request last week that the Supreme Court temporarily block the law so that he can address the matter once he takes office.
The deadline set by the law for TikTok to be sold or shut down is Jan. 19, the day before Mr. Trump’s inauguration.
“This unfortunate timing,” his brief said, “interferes with President Trump’s ability to manage the United States’ foreign policy and to pursue a resolution to both protect national security and save a social-media platform that provides a popular vehicle for 170 million Americans to exercise their core First Amendment rights.”
The law allows the president to extend the deadline for 90 days in limited circumstances. But that provision does not appear to apply, as it requires the president to certify to Congress that there has been significant progress toward a sale backed by “relevant binding legal agreements.”
TikTok’s brief stressed that the First Amendment protects Americans’ access to the speech of foreign adversaries even if it is propaganda. The alternative to outright censorship, they wrote, is a legal requirement that the source of the speech be disclosed.
“Disclosure is the time-tested, least-restrictive alternative to address a concern the public is being misled about the source or nature of speech received — including in the foreign-affairs and national-security contexts,” TikTok’s brief said.
The users’ brief echoed the point. “The most our customs and case law permit,” it said, “is a requirement to disclose foreign influence, so the people have full information to decide what to believe.”
The government said that approach would not work. “Such a generic, standing disclosure would be patently ineffective,” Elizabeth B. Prelogar, the U.S. solicitor general, wrote on Friday.
In a brief filed last week in the case, TikTok v. Garland, No. 24-656, the government said foreign propaganda may be addressed without violating the Constitution.
“The First Amendment would not have required our nation to tolerate Soviet ownership and control of American radio stations (or other channels of communication and critical infrastructure) during the Cold War,” the brief said, “and it likewise does not require us to tolerate ownership and control of TikTok by a foreign adversary today.”
The users’ brief disputed that statement. “In fact,” the brief said, “the United States tolerated the publication of Pravda — the prototypical tool of Soviet propaganda — in this country at the height of the Cold War.”
TikTok itself said the government was wrong to fault it for its failure to “squarely deny” an assertion that “ByteDance has engaged in censorship or manipulated content on its platforms at the direction of” the Chinese government.
Censorship is “a loaded term,” TikTok’s brief said. In any event, the brief added, “petitioners do squarely deny that TikTok has ever removed or restricted content in other countries at China’s request.”