(CNN) A secret court case apparently about a grand jury subpoena from special counsel Robert Mueller's investigation gained a little more clarity Tuesday night after a court ruling revealed the subpoena challenger is an unnamed company owned by a foreign country.

The Justice Department had asked the company to turn over "information" about its commercial activity in a criminal investigation and a federal appeals court is forcing the unnamed company to comply with the subpoena.

The ruling came four days after lawyers argued in secret for more than an hour before a panel of three appellate judges on the US Court of Appeals for the District of Columbia Circuit. The lawyers involved were never seen going into or out of that hearing on Friday, because the court security locked down an entire floor of the federal courthouse in DC for it.

But CNN had spotted attorneys from Mueller's team returning to their office shortly after the hearing ended, and previous CNN reporting on court activity found that Mueller's team had fought with an unknown opponent in September and October over the grand jury matter, which led to the appeal. Politico also previously reported that it had learned the sealed grand jury case had a filing in it from Mueller's team.

The judgment from the appeals court on Tuesday carries possible fines for each day the company doesn't comply with the subpoena.

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