The court’s action means the corporation, which has not been identified, must provide information to the prosecutor or face financial penalties. The court’s two-sentence order gave no reasons and provided no details.

Almost everything about the case has been cloaked in secrecy. But a three-page order issued on Dec. 18 and a more detailed opinion studded with blacked-out passages issued Tuesday after the Supreme Court acted, both from the U.S. Court of Appeals for the District of Columbia Circuit, provided a few hints.

Judges David S. Tatel and Thomas B. Griffith joined the appeal’s court’s unsigned majority opinion, and Judge Stephen F. Williams agreed with the outcome but not all of the majority’s reasoning.

An unnamed foreign government, referred to in the rulings as Country A, owns the corporation, the panel said.

The appeals courtr rejected the corporation’s argument that it could not be forced to comply with the subpoena under a federal law that provides immunity from lawsuits to foreign governments in some circumstances. Even if that law applied to cases concerning grand jury subpoenas, the panel ruled, the law makes an exception for foreign governments’ commercial activities.

The panel also rejected the corporation’s argument that the subpoena was “unreasonable and oppressive” because complying with it would require the corporation to violate one of its home country’s laws.

“The text of the foreign law provision the corporation relies on does not support its position,” the panel wrote, adding that explanations from the corporation’s lawyers and “a regulator from Country A” were unpersuasive.

“Consequently,” the panel wrote, “we are unconvinced that Country A’s law truly prohibits the Corporation from complying with the subpoena.”

The appeals court’s opinion affirmed a sealed ruling by Chief Judge Beryl A. Howell of the U.S. District Court in Washington that had held the corporation in contempt and imposed a fine of $50,000 per day until it complied with the subpoena.

On Dec. 22, in a sealed filing, the corporation asked the Supreme Court to stay Howell’s ruling. The next day, Chief Judge John Roberts temporarily put the matter on hold, ordering the government to file a response by Dec. 31. In the meantime, he wrote, the penalties imposed by Howell would not mount.

Such administrative stays issued by a single justice are usually meant to do no more than maintain the status quo while the full court considers what to do in the case.

Tuesday’s order vacated the chief justice’s temporary stay.

There is nothing in public court documents indicating that the prosecutor involved is Mueller. But the case has involved unusual secrecy even by the standards of grand jury subpoenas.

When the appeals court heard arguments behind closed doors, security officers cleared an entire floor of the courthouse so reporters could not see who the lawyers were as they went in and exited.

Politico wrote in October that one of its reporters had overheard an unidentified lawyer in the appeals court clerk’s office asking to see a sealed filing from the special counsel so his law firm could draft its response. The exchange with the man, who refused to identify himself, took place on the same day that a sealed filing was due in the mystery case.

And CNN has said its reporters twice saw a team of lawyers working for Mueller, including Michael Dreeben, an appellate specialist, going into a sealed courtroom to argue before Howell against an unknown litigant, including on a day when she later handed down a ruling in the sealed case.

This article originally appeared in The New York Times.