The National Security Agency headquarters in Fort Meade, Md. (NSA via Getty Images)

The Obama administration and the U.S. intelligence community, under growing public pressure to justify the National Security Agency's domestic surveillance capabilities, have finally offered up a piece of evidence for their case that the program to track Americans' phone call metadata is necessary to protect national security: a series of wire transfers, worth $8,500 in all, from San Diego to Somalia. In 2008.

The case is more significant than it sounds, but not by much. The money, sent by a 36-year-old cab driver named Basaaly Moalin who'd previously been injured during fighting in Somalia, allegedly went to senior members of an al-Qaeda-allied terrorist group in Somalia called al-Shabaab. That would be material support of terrorism, a serious crime. But it's not much relative to the vast extent and scope of the NSA's programs.

Still, amazingly, as The Washington Post's Ellen Nakashima writes in reporting on the San Diego case, "Senior intelligence officials have offered it as their primary example of the unique value of a National Security Agency program that collects tens of millions of phone records from Americans."

That seems a little like justifying the installation of thousands of traffic cameras at every major intersection in the United States by arguing that one of them once caught someone speeding five years ago. Opponents of the program are not really convinced.

"The notion that this case could be used to justify a mass collection of data is mind-boggling, considering it’s $8,500 that went to Somalia," Joshua Dratel, Moalin's lawyer, told The Post. (He denies that his client sent money to al-Shabaab.)

Sen. Mark Udall (D-Colo.) also argued that this single case is not really sufficient for justifying the NSA's program allowing it to track U.S. phone users' metadata, which includes information about who they called, when and for how long, but does not record the content of the call. Udall has been a critic of the NSA's domestic programs.

"There’s no reason why NSA needed to have its own database containing the phone records of millions of innocent Americans in order to get the information related to Moalin," the senator told The Post. “It could have just as easily gone directly to the phone companies with an individualized court order."

Here's how the phone metadata program is said to have aided the investigation. The NSA, Nakashima reports, had turned up a phone number in Somalia it believed was linked to al-Shabaab. They ran the number through their database of U.S. phone record metadata – that database is the controversial part – and found it had sent or received calls from Moalin's own phone in San Diego. They passed this on to the FBI, which got court approval to tap Moalin's phone as part of an investigation that found evidence, they say, showing that he had wired $8,500 to members of al-Shabaab.

In the NSA's defense, it certainly appears that the phone metadata program played an instrumental role in this case. And one hopes that this is not the only such success in the program's history, perhaps just the only one that can be publicly disclosed without compromising sensitive information or ongoing investigations. But if the Obama administration and/or the U.S. intelligence community are hoping to persuade Americans that the phone metadata collection program is necessary for national security, this five-year-old $8,500 case doesn't seem to be doing the trick.