In a rare act of national government unity, the Supreme Court on Friday joined the other two branches in a historic effort to protect tens of millions of Americans from having vast amounts of their private data stolen when they use a hugely popular social media platform, TikTok.

TikTok is a six-year-old, Chinese-owned online venue of entertainment and wide-ranging discussion used by 170 million Americans amid a much larger electronic community around the globe.

The Court’s new ruling, with none of the nine Justices dissenting, upheld a nine-month-old federal law that seeks to protect Americans who use TikTok from a threat that the government says is due to the close tie between TikTok and the communist government of China.

The decision raised the immediate prospect that TikToik may have to shut down entirely in the United States, and soon, if it does not work out a deal for its operations in this country to be sold by its Chinese ownership to a new owner not linked to a U.S. “adversary.” The law mandating such a sale is due to go into effect on Sunday.

Friday’s ruling was cautious, as the Court has tended to be in facing difficult new questions about laws governing modern technology, and it was narrow in its legal scope.

Here are some of the limits of the decision:

• The Court refused even to consider the federal government’s argument that the sale of ownership was necessary to prevent China’s communist government from secretly manipulating the content on TikTok by inserting propaganda or disinformation in attempts to undermine American democracy, leadership and institutions. The decision was limited to the rationale that Americans needed protection from the theft of their data. That, it said, was enough to support the law’s constitutionality as it applied to TikTok.
• The Court also refused to consider secret data that the government had assembled, including statements under oath by senior intelligence officials, to justify the ban as a way to prevent content-manipulation.
• It only “assumed” for purposes of this ruling that TikTok’s operations in the U.S. were protected by the free expression principles of the Constitution’s First Amendment. That part of the decision was met with a two-page, separate “concurring” opinion by Justice Sonia Sotomayor, arguing that this point was firmly established by the Court’s constitutional precedents.
• The decision applied a more lenient constitutional test in upholding the law as applied to TikTok – that is, “intermediate scrutiny.” It did so because it interpreted the law as avoiding direct government controls on what was seen or said on TikTok. The Court most often uses the most demanding test, “strict scrutiny,” when judging whether a law curbs free speech. A law that fails “strict scrutiny” is almost always struck down.
• The ruling treated TikTok as a unique source of the problem of harvesting Americans’ private data, because its main electronic mechanisms are owned and closely supervised by the Chinese government. The Court thus said that the law did not improperly single out TikTok.
• The Court’s main 20-page opinion was issued in the name of the full Court – that is, it was issued “Per Curiam” (Latin for “by the Court”), meaning that no single Justice would be named as the author of that document. It probably, but not definitely, can mean that the resulting opinion was a group effort. Parts of it, though, seemed to be in the cautious vernacular that Chief Justice John Roberts prefers to write.

Aside from Justice Sotomayor’s brief objection to the First Amendment test the main opinion applied, Justice Neil M. Gorsuch was the only member of the Court to write at any length to express several points suggesting he would have been even more cautious. He wrote that he supported only the bottom line: that is, upholding the law as applied only to TikTok. He went on to express his approval of the main opinion’s limiting points. His writing seemed animated mostly by the Court’s speedy decision – a substantial opinion issued only seven days after a hearing, a rare pace for the Justices.

Under the law, which was passed with huge majorities in Congress nine months ago and was swiftly signed by President Biden, the ban is set to take effect on Sunday if TikTok is not sold to a new owner by then. TikTok and groups of users had sued to block the ban in May, and the constitutional dispute moved rapidly to the Supreme Court, first going through a lower court in Washington. From the filing of the challengers’ appeal with the Justices in mid-December, the case sped to a conclusion in less than five weeks.

The narrowness of the ruling may have the effect of providing only limited constitutional guidance as Congress and the Executive Branch continue their years-long effort to restrain the power of online behemoths that now dominate the information marketplace around the world. But if the decision does mean that the U.S. government can order a change in ownership without violating free expression rights, and does not directly control content, that may have some promise.

What happens next for TikTok and its American community of users – almost half of the nation’s population — is far from certain. The ban is not self-executing and the White House reacted to the Court’s ruling by saying: “Given the sheer fact of timing, this Administration recognizes that actions to implement the law simply must fall to the next Administration, which takes office on Monday.” The statement added that Biden wants TikTok to remain available to Americans but under ownership that does not pose a national security threat.

Varying news stories in recent days have reports of potential buyers, but no definite buyer has yet emerged.

During his presidential campaign, Trump – now a strong supporter of social media in general and TikTok in particular – had asked the Court to put off a ruling to give him a chance on becoming President to negotiate a deal “to save the platform.” Friday’s opinion did not mention that request; that was not surprising, since the Justices released the ruling just three days before Trump becomes President – hardly time enough to find for him to take part in any significant negotiations of a sale.

As President, though, Trump may be resistant to restraints on TikTok and other major platforms, owned by some of his close associates, including Elon Musk, owner of “X.” Trump personally has had a change of heart; when he was President previously, he attempted to force TikTok to sell its assets in the U.S., but that was blocked in court.