Body Scanners: Known Unknowns

There's been a lot of finger-pointing over why the underwear bomber was able to board a plane; an alphabet soup of government agencies can shoulder some of the blame. But this rush to buy and roll out body scanners all over the world as soon as humanly possible is a mistake. The ed board at the Washington Post has even drunk the pro-scanner Kool-Aid. But Americans are being sold a bill of goods . Here's why this rush to electronically strip search everyone is mistake: It's not clear that body scanners work.

The UK's Independent reported Sunday:

Tests by scientists in the team at Qinetiq […] showed the millimetre-wave scanners picked up shrapnel and heavy wax and metal, but plastic, chemicals and liquids were missed.

If a material is low density, such as powder, liquid or thin plastic — as well as the passenger's clothing — the millimetre waves pass through and the object is not shown on screen. High-density material such as metal knives, guns and dense plastic such as C4 explosive reflect the millimetre waves and leave an image of the object. (emphasis added)

Abdulmutallab, of course, carried three ounces of powder and a syringe containing liquid.

At London’s Heathrow airport, a four-year test of the scanners resulted in a decision to discontinue their use, according to the London-based group Privacy International. The UK Telegraph reports:

the Government is likely to call for the reactivation of four full body scanners which have been in storage at Heathrow for some time. The machines, which are now six years old, will have to be updated...

It kind of speaks for itself if the security people at Heathrow played with the scanners for several years and then just put them in storage.

As many, including President Obama, have said and written repeatedly, these agencies had all the intelligence that was needed to stop and question Abdulmutallab, but a breakdown in communication between agencies allowed him to board that plane bound for Detroit.

When bad things like this happen, it's in our nature to overreact and clamp down on everything we possibly can. But politicians' rush to "do something" inevitably leads to ineffective measures designed to make us feel better, but not necessarily safer.

Rolling out more body scanners are an example of this kind of ineffective measure.