Schneier on Security
A blog covering security and security technology.
November 24, 2004
Behavioral Assessment Profiling
On Dec. 14, 1999, Ahmed Ressam tried to enter the United States from Canada at Port Angeles, Wash. He had a suitcase bomb in the trunk of his car. A US customs agent, Diana Dean, questioned him at the border. He was fidgeting, sweaty, and jittery. He avoided eye contact. In Dean's own words, he was acting "hinky." Ressam's car was eventually searched, and he was arrested.
It wasn't any one thing that tipped Dean off; it was everything encompassed in the slang term "hinky." But it worked. The reason there wasn't a bombing at Los Angeles International Airport around Christmas 1999 was because a trained, knowledgeable security person was paying attention.
This is "behavioral assessment" profiling. It's what customs agents do at borders all the time. It's what the Israeli police do to protect their airport and airplanes. And it's a new pilot program in the United States at Boston's Logan Airport. Behavioral profiling is dangerous because it's easy to abuse, but it's also the best thing we can do to improve the security of our air passenger system.
Behavioral profiling is not the same as computerized passenger profiling. The latter has been in place for years. It's a secret system, and it's a mess. Sometimes airlines decided who would undergo secondary screening, and they would choose people based on ticket purchase, frequent-flyer status, and similarity to names on government watch lists. CAPPS-2 was to follow, evaluating people based on government and commercial databases and assigning a "risk" score. This system was scrapped after public outcry, but another profiling system called Secure Flight will debut next year. Again, details are secret.
The problem with computerized passenger profiling is that it simply doesn't work. Terrorists don't fit a profile and cannot be plucked out of crowds by computers. Terrorists are European, Asian, African, Hispanic, and Middle Eastern, male and female, young and old. Richard Reid, the shoe bomber, was British with a Jamaican father. Jose Padilla, arrested in Chicago in 2002 as a "dirty bomb" suspect, was a Hispanic-American. Timothy McVeigh was a white American. So was the Unabomber, who once taught mathematics at the University of California, Berkeley. The Chechens who blew up two Russian planes last August were female. Recent reports indicate that Al Qaeda is recruiting Europeans for further attacks on the United States.
Terrorists can buy plane tickets -- either one way or round trip -- with cash or credit cards. Mohamed Atta, the leader of the 9/11 plot, had a frequent-flyer gold card. They are a surprisingly diverse group of people, and any computer profiling system will just make it easier for those who don't meet the profile.
Behavioral assessment profiling is different. It cuts through all of those superficial profiling characteristics and centers on the person. State police are trained as screeners in order to look for suspicious conduct such as furtiveness or undue anxiety. Already at Logan Airport, the program has caught 20 people who were either in the country illegally or had outstanding warrants of one kind or another.
Earlier this month the ACLU of Massachusetts filed a lawsuit challenging the constitutionality of behavioral assessment profiling. The lawsuit is unlikely to succeed; the principle of "implied consent" that has been used to uphold the legality of passenger and baggage screening will almost certainly be applied in this case as well.
But the ACLU has it wrong. Behavioral assessment profiling isn't the problem. Abuse of behavioral profiling is the problem, and the ACLU has correctly identified where it can go wrong. If policemen fall back on naive profiling by race, ethnicity, age, gender -- characteristics not relevant to security -- they're little better than a computer. Instead of "driving while black," the police will face accusations of harassing people for the infraction of "flying while Arab." Their actions will increase racial tensions and make them less likely to notice the real threats. And we'll all be less safe as a result.
Behavioral assessment profiling isn't a "silver bullet." It needs to be part of a layered security system, one that includes passenger baggage screening, airport employee screening, and random security checks. It's best implemented not by police but by specially trained federal officers. These officers could be deployed at airports, sports stadiums, political conventions -- anywhere terrorism is a risk because the target is attractive. Done properly, this is the best thing to happen to air passenger security since reinforcing the cockpit door.
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