Our elite media has been repeatedly suckered into trumpeting glaringly unsupported assertions about the number of Guantanamo detainees that have “returned” to the battlefield. This was quite a week for it.

The most blatant and distressing previous object lesson came early last summer, when New York Times Public Editor Clark Hoyt appropriately spanked reporter Elisabeth Bumiller and her editors for a top-of-the-front-page story in late May that was “seriously flawed and greatly overplayed.” Hoyt wrote that the story, which appeared under the headline 1 in 7 Detainees Rejoined Jihad, Pentagon Finds “demonstrated again the dangers when editors run with exclusive leaked material in politically charged circumstances and fail to push back skeptically.”

Entirely by coincidence, of course, Bumiller’s article, based on a secret Pentagon report, provided a handy talking point for former vice president Cheney later that day, when he snarlingly attempted to rebut President Obama’s major address on national security speech later.

Bumiller’s reporting failure also earned her an editor’s note appended to her story, and a scolding op-ed.

And yet, amazingly enough, eight months later – now in the midst of attempts by Gitmo dead-enders to turn the aborted Exploding Christmas Underpants plot into a political cudgel – Bumiller is at it again, though this time chasing Bloomberg, et al., rather than leading the pack.

This time it’s one in five former detainees who have “engaged in, or is suspected of engaging in, terrorism or militant activity.” And here’s the sum total of what Bumiller learned from her previous experience:

Civil liberties and human rights groups sharply criticized the May 2009 report and earlier Pentagon reports during the Bush administration concluding that substantial numbers of former Guantánamo detainees had engaged in terrorism or militant activity. The groups said that the information was too vague to be credible and amounted to propaganda in favor of keeping the prison open.

But it’s not just that the Pentagon’s assertions are suspicious on their face. As it happens, a series of studies directed by Seton Hall Law Professor Mark Denbeaux has been effectively picking them apart for years. (A response to the latest spate of stories will be coming out on Monday.)

Among the other (little, inconsequential) things the Seton Hall reports have pointed out is that the Pentagon, in all the times it has leaked on the topic, has nevertheless consistently refused to provide names that would allow anyone to actually verify most of its claims. There’s the issue of how they define “returning to the fight” – it apparently includes detainees speaking out publicly against their incarceration. There’s the fact that officials, if you press them, acknowledge they don’t really track former detainees – so this is largely speculative. And there’s the specious use of the term “return” – given that most of the detainees who were released weren’t found on the battlefield in the first place and were never formally charged with anything.

From Denbeaux’s December 2007 report:

The Department of Defense has publicly insisted that “just short of 30” former Guantánamo detainees have “returned” to the battlefield… but to date the Department has described at most 15 possible recidivists, and has identified only seven of these individuals by name. According to the data provided by the Department of Defense.. at least eight of the 15 individuals alleged by the Government to have “returned to the fight” are accused of nothing more than speaking critically of the Government’s detention policies.

From his January 2009 report:

The Department of Defense does not keep track of released detainees nor does it follow their post release conduct.

Denbeaux calls this week’s outrageous Pentagon assertions the latest example of what he calls “numbers without names and trends without numbers.” He told me he’s outraged it’s been so widely picked up — including by the Times.

“I don’t see what the point is of a public editor criticizing a story for the New York Times if they’re going to republish it a year later,” he told me.

Gullible, amnesiac journalists are a dangerous thing. Is our profession really incapable of learning anything from its mistakes?