A federal appeals court on Tuesday considered whether the Justice Department must make public a legal opinion on the scope of the FBI’s surveillance authority.

The case marks the first time that the U.S. Court of Appeals for the D.C. Circuit has addressed the question of whether opinions from the government’s legal advisers must be disclosed under the Freedom of Information Act.

At issue is a January 2010 memo from the Justice Department’s Office of Legal Counsel that allowed the FBI to informally gather customer phone call records from telecommunications companies. The office, according to court filings, found that under certain circumstances, the bureau could collect the data “without legal process,” such as a court order or subpoena, or a “qualifying emergency.”

The FBI has said that the bureau stopped the controversial practice in 2006, but the issue of secret government surveillance has taken on renewed significance after it was revealed this past summer that the National Security Agency had obtained billions of domestic phone call records. The broad collection of Americans’ data was authorized by the Foreign Intelligence Surveillance Court, which operates in secret.

Mark Rumold, a lawyer for the Electronic Frontier Foundation, the civil liberties organization that brought the lawsuit, called the FBI memo a “blossoming example of secret surveillance law” and said that the legal rationale in the memo could still be used by other intelligence agencies.

“When the government is allowed to continue to interpret the law in secret, that creates problems for the privacy rights of Americans,” he said.

Attorneys for the government argued — and at least one judge on Tuesday’s three-member panel agreed — that the role of the Office of Legal Counsel is to help the attorney general provide legal advice to the president, not to set policy.

Requiring the Justice Department to release the memo, the lawyers said in court filings, would “chill” free-flowing discussions inside the government and hinder the office’s ability to provide “confidential legal advice to federal agencies as they develop their policies.”

The Justice Department characterized the 11-page memo in court filings as “simply advice” to the FBI with no “legal effect on the rights or obligations of telephone companies or their customers.”

Judge David B. Sentelle agreed that the memo was part of the “deliberative process” and protected by a legal privilege designed to promote candid, confidential discussions regarding policy decisions.

“The office is there to give advice,” he said, skeptically quizzing Rumold. “You’re saying they can’t give advice unless it’s publicly disclosed. That doesn’t make sense.”

Under questioning by newly appointed Judge Sri Srinivasan, Justice Department lawyer Daniel Tenny conceded that federal agencies do not typically ignore advice from the Office of Legal Counsel. But he noted that the memo at issue in this case was not adopted by the FBI, but was used as a justification for its past practice when the bureau was being questioned by the department’s inspector general.

Judge Harry T. Edwards followed up, asking, “Couldn’t they try to do it again?”

The FBI turned to the Office of Legal Counsel in late 2009 in response to criticism from the inspector general about its practice of informally obtaining telephone toll information by sending so-called exigent letters to telecommunications providers. The bureau stopped using emergency letters to track phone call information in 2006.

The Office of Legal Counsel has in the past voluntarily released some of its opinions. The Obama administration, for instance, disclosed memos about the CIA’s interrogation program during the George W. Bush administration. But the office also has been criticized for not making public memos that provide the legal rationale for controversial government programs such as the use of drones for targeted killings.

In court filings, the civil liberties organization wrote that the office’s opinions are “conclusive and binding interpretations of law” and essentially represent the legal positions of the executive branch.

A lower court judge, however, found that the government properly withheld the memo under an exception to the Freedom of Information Act. The Electronic Frontier Foundation appealed and was joined in an amicus brief by several other organizations, including the American Civil Liberties Union, Citizens for Responsibility and Ethics in Washington, and The Washington Post.