Israel has been dealing with the threat of airborne terrorism for decades, 
and their air transport system has an excellent track record of detecting 
potential terrorist attacks before they occur. Based on Israeli 
experience, it appears that the best way to detect terrorists that are 
trying to board airplanes is to behaviorally profile them. Even for a 
highly indoctrinated terrorist, it's difficult to remain calm during the 
minutes before the terrorist act is committed. Law officers can be trained 
to detect this nervousness and then nominate the person for further 
screening. Duane Woerth, president of the Air Line Pilots Association, 
provided the following testimony to the United States Congress: "The 
Israeli aviation security-screening model, widely regarded as the world's 
best, is human-centered and trust-based. Information is collected on 
passengers before they arrive to the airport and they are physically 
screened and queried in concert with that knowledge. Trained personnel 
assess individual characteristics that are indicative of deception and 
engage passengers in conversation and questioning to establish the purpose 
and authenticity of an individual's travel plans. Considerably less time 
and resources are spent on physically screening those who are deemed to be 
non-threat persons and traveling for legitimate purposes." Woerth 
continued by saying that US airports erroneously assume "that everyone 
poses a potential threat to aviation security. The truth is that the vast 
majority of individuals, including airline pilots, do not pose any kind of 
threat to aviation . . . our screening resources are greatly diluted by 
giving the same degree of physical security to an Air Force Reserve 
general and airline pilot as is given to a federal prison parolee." Some 
limited forms of behavioral profiling have begun to appear in American 
airports, but not to the extent that it has been used in Israel. There are 
several reasons for this. Perhaps most important is that the Israelis 
perform behavioral profiling in concert with ethnic profiling, paying more 
attention to people who look Arabic. This racial profiling is inherent to 
the Israeli notion that, probabilistically speaking, different types of 
people pose different levels of threat. Many Americans may be hesitant to 
embrace such a blatant bias, since it seems to place speculative guilt on 
many people who are not actually terrorists.

It is statistically true that, in the current era, a white elderly woman 
is less likely to carry a suicide bomb than a young Arabic man. Despite 
this statistic, it may be preferable to live in a society in which we act 
as if the likelihood of being a terrorist is scattered randomly across all 
demographics. If this is the choice we make, then we *all* have to put up 
with having our shoes checked for explosives, and having ourselves 
randomly selected to be patted down, and having to engage in other 
security measures which cast a broad net. The idea behind banning liquids 
on planes is not that it will deter a highly skilled attacker. The idea is 
that it will make it more difficult for a terrorist with average 
intelligence to cause unspeakably horrific damage. Furthermore, the hope 
is that, in concert with other a multitude of other mechanisms like X-rays 
and metal detectors, banning liquids will help to thwart the vast majority 
of more sophisticated attacks. We all have to put up with these security 
hassles because, as a society, we don't want airports to subject Muslims 
or Arabic-looking people to a disproportionate number of security checks 
and let everyone else stroll off to their destination gate.

With respect to the specific controversy over the liquid ban, airports 
have an obligation to cover the most obvious threat vectors, particularly 
those which the intelligence community has deemed likely to be used in the 
near future. Just because we can't detect all threats with perfect 
accuracy is no reason to stop trying to detect them. Judging from Daniel's 
email, it seems like American airports are being fairly lax about checking 
whether passengers are actually carrying liquids. The same is not true in 
the UK, where I currently am. For the past four days in the UK, you 
haven't been allowed to bring *any* carry-on items onto the plane, with 
the exception of a passport, prescription medication, and baby formula, 
all of which must be carried in a clear plastic bag; any baby formula must 
be tasted by a parent in front of a security agent. All of your luggage 
must be opened and physically inspected by a security agent, and there is 
an extremely high probability that your body will be patted down for any 
potentially dangerous items, including liquids. The British aren't kidding 
around, and their ban on liquids is serious. If the American airports are 
not being this intensive, then I can see how their "ban" on liquids might 
seem silly. Nevertheless, I think that every bit helps, and when I return 
to America in two weeks, I'll personally feel safer when I step onto my 
plane at Heathrow and I know that a relevant threat vector has been 
extensively checked by the British Airport Authority.

~j