Privacy advocates are outraged as the scanners show basically a nude image of the passenger -- with genitals and breasts blurred by software (though the raw image is fully nude).  However, there may be a far greater problem with the scanners. According to British government officials -- they don't work.

The British Department for Transport (DfT) and the Home Office tested the new 3D scanners thoroughly and found that while they were relatively accurate in catching high-density materials that pat-downs missed (such as knives, box-cutters, or other problem items), they failed to detect most low-density items, including bags of liquid.

The Christmas Day bomber used a 3 oz. package of the chemical powder PETN (pentaerythritol tetranitrate), disguised in his crotch.  Hard to detect in a pat down, British politicians familiar with the country's internal research say that "millimeter-wave" scanners would also likely fail to spot the bag of low-density chemical explosives.

According to Ben Wallace, the UK Conservative MP, tests showed that the new scanners failed to detect a variety of low-density materials, including, plastic, chemicals and liquids.  The waves pass through these materials, hitting the body and then bouncing back, revealing only the underlying skin.

Like the U.S., the UK is now considering adopting the scanners on a broad basis.  However, emerging evidence from government studies on the scanners indicates that the rollout may be nothing more than a pricey game of "security theater" designed to make people feel safe, while doing little in reality.  This is significant, considering the investment may amount to hundreds of millions, if not billions of dollars, an expense that will surely be passed on to taxpayers.

Mr. Wallace comments, "[UK Prime Minister] Gordon Brown is grasping at headlines if he thinks buying a couple of scanners will make us safer. It is too little, too late. Under his leadership, he starved the defence research budget that could have funded a comprehensive solution while at the same time he has weakened our border security.  Scanners cannot provide a comprehensive solution on their own. We must now start to ask if national security demands the use of profiling."

Mr. Wallace is among the politicians in the U.S., UK, and abroad that's suggesting some sort of profiling system as an alternative to more effectively increase security.  Such a system might involve additional searches of foreign nationals, particularly from volatile regions like the Middle East and Africa, while potentially lightening the searches on certain groups, like the elderly.