The federal government filed a response Friday in a mysterious case believed to be related to special counsel Robert Mueller's Russia investigation involving an unnamed, foreign-owned company.

The filing, which arrived before the Dec. 31 deadline set by Supreme Court Chief Justice John Roberts, is under seal and its contents are hidden from public view.

The company, known only as "Corporation A" and owned by "Country A," lost its challenge last week against having to comply with a grand jury subpoena thought to have been issued by Mueller.

The U.S. Court of Appeals for the District of Columbia Circuit rejected the challenge by the company to quash the subpoena late Tuesday night, after which the company asked the Supreme Court to get involved.

On Sunday, Roberts issued a temporary administrative stay of contempt on sanctions brought against the company, giving himself or all of the Supreme Court until noon on Monday to consider whether to take up the case.

The Supreme Court also temporarily halted the $5,000-per-week fine the company was incurring for not complying with the subpoena.

"Chief Justice Roberts will now probably refer the unnamed foreign company’s stay application to the full Court, from which the company will need five votes to continue the stay of the district court’s grand jury contempt citation—with a ruling possible by Monday, if not sooner," Steve Vladeck, a CNN Supreme Court analyst and professor at the University of Texas School of Law, said in a series of tweets Friday evening.

"To be clear, such a ruling is only on whether the Court should continue the administrative stay of the contempt citation that the Chief Justice entered last weekend pending what is presumably a forthcoming petition for certiorari (i.e., full review of the lower court decisions)," he added.