A federal appeals court directed an unidentified corporation on Tuesday to comply with a grand jury subpoena believed to be tied to special counsel Robert Mueller III's probe.

A three-judge panel for the U.S. Court of Appeals for the D.C. Circuit affirmed a lower court ruling by Chief Judge Beryl Howell that denied the state-owned corporation's bid to quash the subpoena.

The corporation's appeal of that ruling led up to a sealed oral argument on Friday that closed an entire floor in the courthouse in an effort to keep the proceedings under wraps.

According to Tuesday's order, the corporation attempted to quash the subpoena by arguing it was immune under the Foreign Sovereign Immunities Act, and by contending the subpoena would have required the corporation to violate its country's domestic law.

But the panel—comprised of Judges David Tatel, Thomas Griffith and Stephen William—was not persuaded, instead taking up the lower court's finding that the corporation was not immunized from the subpoena. The judges also wrote that they were “unconvinced” the foreign country's law “truly prohibits” the corporation from complying.

The judges also agreed with the district court's decision to impose a penalty on the corporation. The lower court had held the corporation in contempt and imposed a “fixed monetary penalty to increase each day the Corporation fails to comply,” according to the order.

“Whether and how that sanction can be executed on remand is a separate question for a later day,” the panel said.

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