Yesterday, I wrote about Jon Corbett's video, in which he demonstrates a method that appears to make it easy to smuggle metal objects (including weapons) through a TSA full-body scanner. The TSA has responded by saying that they still trust the machines, but they won't say why, "for obvious security reasons."

As Wired's David Kravets points out, Corbett is only the most recent critic to take a skeptical look at the efficacy of the expensive, invasive machinery. Other critics include the Government Accountability Office ("the devices might be ineffective") and the Journal of Transportation Security ("terrorists might fool the Rapiscan machines by taping explosive devices to their stomachs").

Corbett responded to the TSA's we-can't-tell-you-or-we'd-have-to-kill-you rebuttal with "You don't believe it? Try it."

“These machines are safe,” Lorie Dankers, a TSA spokeswoman, said in a telephone interview.

In a blog post, the government’s response was that, “For obvious security reasons, we can’t discuss our technology’s detection capability in detail, however TSA conducts extensive testing of all screening technologies in the laboratory and at airports prior to rolling them out to the entire field.”

TSA Pooh-Poohs Video Purporting to Defeat Airport Body Scanners