Updated

A federal judge has ordered the Justice Department to provide Congress with a list of documents that are at the center of a long-running battle over a failed law enforcement program called Operation Fast and Furious.

In a court proceeding Wednesday, U.S. District Judge Amy Berman Jackson set an Oct. 1 deadline for producing the list to the House Oversight and Government Reform Committee.

The Justice Department says the documents should remain confidential and President Barack Obama has invoked executive privilege in an effort to protect them from public disclosure.

The House panel says the Justice Department documents might explain why the department took nearly a year to admit that federal agents had engaged in a controversial law enforcement tactic known as gun-walking.

The Justice Department has long prohibited the risky practice. But the Bureau of Alcohol, Tobacco, Firearms and Explosives used it with disastrous results in a federal law enforcement probe in Arizona, Operation Fast and Furious.

In the operation, federal agents permitted illicitly purchased weapons to be transported unimpeded in an effort to track them to high-level arms traffickers.

Federal agents lost control of some 2,000 weapons and many of them wound up at crime scenes in Mexico and the U.S. Two of the guns were found at the scene of the December 2010 slaying of border agent Brian Terry near the Arizona border city of Nogales.

After Wednesday's court proceeding, Justice Department spokeswoman Emily Pierce said that "we are pleased the judge recognized that executive privilege includes a deliberative process beyond presidential communications" -- a point the department has been arguing in its dispute with Congress.

In court papers, the Justice Department has said that if the courts were to reject a confidentiality claim, Congress could have unfettered access to all information from the executive branch of government aside from presidential communications.

Such a development would be in contravention of the constitutional separation of powers and over two centuries of dealings between the legislative and executive branches, the department said.

The need for some confidentiality in the executive branch is particularly strong in the current case, which involves a congressional demand for information that would reveal the process by which the executive responds to congressional inquiries, the Obama administration added.

Rep. Darrell Issa, R-Calif., the chairman of the House panel, said that the privilege log "will bring us closer to finding out why the Justice Department hid behind false denials in the wake of reckless conduct that contributed to the violent deaths of border patrol agent Brian Terry and countless Mexican citizens."

Congress is trying to get documents that were created after Feb. 4, 2011 -- the day the Justice Department told Sen. Chuck Grassley that ATF "makes every effort to interdict weapons that have been purchased illegally and prevent their transportation to Mexico."

Grassley is the ranking Republican on the Senate Judiciary Committee. In a follow-up on May 2, 2011, the Justice Department told Grassley that "it remains our understanding that ATF's Operation Fast and Furious did not knowingly permit straw buyers to take guns into Mexico."

Three days later, a senior Justice Department official informed the committee that "there's a there there" with respect to the congressional investigation.

On Dec. 2, 2011, the Justice Department withdrew the original Feb. 4 letter which denied that gun-walking had taken place.

The Obama administration says the privilege claim is designed to protect the Justice Department's internal records related to its response to Congress -- specifically, its work file on how it responded to the congressional inquiry after the drafting of the Feb. 4, 2011 letter.

Jackson, the judge in the current case, is an appointee of President Barack Obama.