It is ten years to the day that strict liquid restrictions were imposed on travellers through UK airports. Even though there's very little evidence that these rules have stopped a single attack, they continue to have huge economic costs.
According to The Times:
"One in five security trays scanned by airports still contains drinks, aerosols, sun creams, perfumes or cosmetics which breach the regulations, according to research published today.
More than 140 million tonnes of bottled drinks were confiscated in the past 12 months as passengers went through scanners, Manchester Airports Group (MAG) revealed. It said that confusion over liquids remained the biggest single cause of delays at security queues during peak times."
As security expert Bruce Schneier points out:
"There are two classes of contraband at airport security checkpoints: the class that will get you in trouble if you try to bring it on an airplane, and the class that will cheerily be taken away from you if you try to bring it on an airplane."
The bottle ban falls into the later category. When travellers are stopped by security for having the wrong kind of bottle, they aren't then brought aside for questioning. That'd be too time consuming given the sheer number of accidental rule breakers. In fact, most security officers seem indifferent to what's actually in the bottle. The bottles are simply discarded and the passenger is waived on through. A wannabe attacker could take that risk over and over again.
Indeed, the very basis of the restrictions seem weak. Even if a would-be terrorist wasn't able to bring enough of an explosive on board as part of their liquid allowance, they could still buddy up with a couple others troublemakers and simply mix the explosive liquids together in a bigger bottle bought in duty free.
You may point out that since bringing the rules in there have been no major terrorist attacks on airplanes coming out of UK/US airports. But Matt Ygleisas raises an interesting question. Why don't we see liquid explosive attacks on buses and trains where these strict rules aren't enforced? When a restriction is opposed on one activity, you would expect an increase on activities that are close substitutes. For example, if the Government banned e-cigs we'd expect to see sales of old fashioned tobacco cigarettes up. Yet, for terrorism in the UK we just don't see that substitution effect.
Regardless of their actual safety benefit, "Security Theatre" measures such as these may at least make passengers feel safer. But, ten years on, with millions of passengers ignoring the rules, long waits, and unnecessary waste, it's time to ask – is it worth it?