When government employees believe that classified information in their possession is improperly classified, they “are encouraged and expected” to challenge its classification status, according to President Obama’s executive order 13526 (section 1.8). And sometimes they do.

In Fiscal Year 2012, there were 402 classification challenges filed by government employees. One third of them were granted in whole or in part, according to statistics published by the Information Security Oversight Office.

Such classification challenges have the potential to serve as a powerful internal check on over-classification. But that potential is not yet being fully realized, either because the procedure is unknown to employees or because its use is implicitly discouraged.

“We found that many DOJ officials were unaware of DOJ’s formal classification challenge process,” according to a 2013 Department of Justice Inspector General report.

At the Department of Defense, “few instances were encountered where interviewees challenged a classification,” a DoD IG report said. Although DoD guidance “provides for classification challenges, it does not reflect the intent of E.O. 13526 which states that such challenges are ‘encouraged’.”

By contrast, at the Department of Homeland Security, “DHS senior management we interviewed believes that challenging the classification status of information is part of an employee’s job.” Furthermore, a DHS IG review found, the Department “honors a challenger’s request for anonymity and serves as his or her agent in processing the challenge. DHS has a secure capability to receive information, allegations, or classification challenges.”

The provision for classification challenges in the executive order can only be invoked by authorized holders of the information. Members of the general public cannot file such challenges. Although a member of the public may request declassification review of a particular document under existing standards, he or she is not empowered to dispute the validity of those standards or to challenge the classification status of an entire topical area.

One partial exception to this rule is a Department of Energy regulation in 10 C.F.R. 1045.20 that invites the public to propose the declassification of particular items of information classified under the Atomic Energy Act.

Last June 30, the Federation of American Scientists filed such a petition seeking declassification of “the total size of the U.S. nuclear stockpile and the number of weapons dismantled annually as of the end of each fiscal year from FY 2010 through FY 2013.”

We filed the petition after the Department of Defense refused to release the requested data. Requests for current stockpile information were denied even though — in a major departure from prior government secrecy policy — the Obama Administration in May 2010 had disclosed annual stockpile figures for previous years up through FY 2009. (See Pentagon Reverts to Nuclear Stockpile Secrecy, Secrecy News, July 1, 2013.)

So invoking DOE regulation 10 CFR 1045.20, we asked for reconsideration of this refusal. It is apparently the first time that the DOE regulation has ever been employed by a public petitioner since the provision was adopted in the 1990s.

On April 29, the requested information was disclosed in a State Department Fact Sheet. It reported a stockpile total of 4,804 warheads in September 2013, down from the last published figure of 5,113 in September 2009.

(Hans Kristensen of FAS expressed disappointment at the slow pace of stockpile reductions in recent years here. The Government Accountability Office noted ambiguities in the counting of dismantled warheads here.)

Although the release matched our request, providing neither more nor less information than we asked for, that was merely “serendipitous,” said a US government official. The FAS petition was “not a major driver” of the declassification process, he said. “The White House wanted to get this done all along.”

That may be so. (Although if the White House wanted it disclosed all along, it’s not clear why this information was actively withheld each year for the past four years.)

In any case, the DOE regulation inviting public proposals for declassification is assuming new importance. It now serves as a designated feeder to a new interagency review process for declassification of so-called Formerly Restricted Data (FRD), which is a category of information classified under the Atomic Energy Act.

At least one new petition for declassification has recently been submitted by the National Security Archive, we have another one in the works, and increased public use of the procedure is anticipated.

The DOE regulation extends the power of classification challenges to members of the public. As such, it represents a “best practice” that could usefully be replicated in other agencies, and in the context of national security information generally (not just nuclear matters).

Of course, the key to a successful classification challenge is that it must be reviewed impartially by someone other than the original classifier.