The NSA audit obtained by The Post, dated May 2012, counted 2,776 incidents in the preceding 12 months of unauthorized collection, storage, access to or distribution of legally protected communications. Most were unintended. Many involved failures of due diligence or violations of standard operating procedure. The most serious incidents included a violation of a court order and unauthorized use of data about more than 3,000 Americans and green-card holders.
In a statement in response to questions for this article, the NSA said it attempts to identify problems "at the earliest possible moment, implement mitigation measures wherever possible, and drive the numbers down." The government was made aware of The Post's intention to publish the documents that accompany this article online.
"We're a human-run agency operating in a complex environment with a number of different regulatory regimes, so at times we find ourselves on the wrong side of the line," a senior NSA official said in an interview, speaking with White House permission on the condition of anonymity.
"You can look at it as a percentage of our total activity that occurs each day," he said. "You look at a number in absolute terms that looks big, and when you look at it in relative terms, it looks a little different."
There is no reliable way to calculate from the number of recorded compliance issues how many Americans have had their communications improperly collected, stored or distributed by the NSA.
The causes and severity of NSA infractions vary widely. One in 10 incidents is attributed to a typographical error in which an analyst enters an incorrect query and retrieves data about U.S phone calls or e-mails.
But the more serious lapses include unauthorized access to intercepted communications, the distribution of protected content and the use of automated systems without built-in safeguards to prevent unlawful surveillance.