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WASHINGTON — An unidentified foreign government is asking the Supreme Court to get involved in a case that may be part of special counsel Robert Mueller's Russia investigation.

The justices on Tuesday granted the government's request to file a censored version of an appeal to the high court in which the country is fighting a grand jury subpoena and a $50,000-a-day fine for not complying with the subpoena.

The appeal doesn't identify the country, a company it controls or even the lawyers who are representing it. But the appeal says the justices should make clear that a federal law that generally protects foreign governments from civil lawsuits in the U.S. also shields them in criminal cases.

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The justices had previously refused to block the subpoena and fine on an emergency basis.

A three-judge panel of the federal appeals court in Washington had in December upheld the issuance of the subpoena and a contempt order issued by a district court judge when the company, identified only as wholly owned by a foreign country, failed to comply.

The country says that the appellate ruling would upset foreign relations in a big way if allowed to stand. It says the U.S. Circuit Court of Appeals for the District of Columbia is "the first appellate court in American history to exercise criminal jurisdiction over a foreign state."

The country says it is immune from being subpoenaed under the Foreign Sovereign Immunities Act and that complying would require it to violate its own laws.

The U.S. government has until Feb. 21 to respond to the appeal. An uncensored, sealed version of the appeal also has been filed with the court.

Both Politico and The Washington Post have reported that the subpoena apparently relates to the Mueller investigation. Prosecutors have been trying to obtain information from the foreign-owned company since last summer, Judge Stephen Williams wrote in an opinion that was released by the appeals court earlier in January.

The case has been shrouded in secrecy as it has moved through the court system. Federal marshals closed an entire floor of the federal courthouse in Washington last month when the case was argued before the three-judge appellate panel. The move stymied the efforts of a group of about 15 reporters to see whether any Mueller team members or other participants had entered the hearing room.