After Congress found the nation's top law enforcement officer in contempt Thursday, the Department of Justice quickly wrote a letter to House Speaker John Boehner informing him that it will not prosecute U.S. Attorney General Eric Holder for withholding documents in a congressional investigation of the Fast and Furious gun walking operation.

"The longstanding position of the Department of Justice has been and remains that we will not prosecute an Executive Branch official under the contempt of Congress statute for withholding subpoenaed documents pursuant to a presidential assertion of executive privilege," James M. Cole, the deputy attorney general, wrote in a letter dated June 28 and addressed to the Speaker.

The House voted Thursday to pass a resolution which for the first time in U.S. history found a sitting U.S. attorney general in criminal contempt of Congress.

DOJ's response does not come as a complete surprise. Historically when Congress votes to hold someone in contempt, the report is referred to the U.S attorney of the District of Columbia for prosecution. But Holder's case is unprecedented, going after the same official tasked with overseeing the department that's charged with enforcing contempt.

Today's letter, which was also sent to Democratic Leader Nancy Pelosi, and Reps. Darrell Issa and Elijah Cummings, goes on to cite legal precedent of executive privilege claims during Presidents Ronald Reagan and George W. Bush's administrations as justification for its refusal to prosecute Holder.

"Consistent with this uniform position and practice, the Department has determined that the Attorney General's response to the subpoena issued by the Committee on Oversight and Government Reform does not constitute a crime, and therefore the Department will not bring the congressional contempt citation before a grand jury or take any other action to prosecute the Attorney General," the letter concludes.

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Congressional GOP sources expect the Oversight and Government Reform committee to work with the House general counsel to pursue the case in federal court with the hope that a court will ultimately compel Holder to hand over the outstanding documents.

Republicans also passed a second resolution Thursday that found Holder in civil contempt of Congress. That resolution authorizes the Committee on Oversight and Government Reform "to initiate or intervene in judicial proceedings to enforce certain subpoenas."

Still, that process could take months or even years.

"It is regrettable that the political leadership of the Justice Department is trying to intervene in an effort to prevent the U.S. Attorney for the District of Columbia from making an independent decision about whether to prosecute this case," Frederick Hill, director of communications at the Oversight committee, said, reacting to the letter.