Security Screening: Science or Sorcery? Commentary
Security Screening: Science or Sorcery?
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JURIST Guest Columnist Tung Yin, of Lewis and Clark Law School, discusses the effectiveness of TSA screening policies and how those policies affect our privacy rights…

In the fall of 2001, I went on the market to become a law professor, and I was fortunate enough to do a fair amount of flying for interviews. This was in the tense days following the 9/11 attacks before there was a Transportation and Security Agency (TSA), but when there was seemingly racial and ethnic profiling being used for secondary screening purposes. The millimeter wave and backscatter X-ray detectors were yet to be developed, so security screening consisted of sending passengers through the magnetometers and then subjecting a subset of persons to a manual inspection of their carry-on bags. In addition, there would be an additional secondary screening at the airport gate before boarding the flight. On one of my flights, there was a group of five men dressed in business suits who were speaking jovially to one another. All five were “randomly” selected for secondary screening.

All five appeared to be of Middle Eastern descent.

The TSA Behavioral Detection Programs

If the recent suit ACLU v. TSA [PDF] is to be believed, not much has changed in 14 years. TSA currently uses “behavioral detection” programs to select airline passengers for secondary inspections and questioning. An apparently leaked TSA document reveals that “[e]xcessive yawning, repetitive grooming gestures and excessive body odor” are among the behaviors that can trigger additional scrutiny, on the theory that they indicate a desire “to appear disinterested in the screening process.”

However, numerous stories in the mass media have alleged that these profiling programs have disproportionately targeted racial minorities, particularly those of Middle Eastern descent. In addition, government auditors have criticized the detection programs as being useless and scientifically invalid. In its Freedom of Information Act (FOIA) request, the American Civil Liberties Union (ACLU) was seeking:

the release of records concerning the scientific basis for the TSA’s behavior detection programs; policies, procedures, and guidance pertaining to the programs and their implementation; training and course materials for employees involved in behavior detection activities; records concerning the analysis or assessment of behavior detection programs and their implementation; data regarding referrals for additional screening and subsequent arrests; records related to the SPOT database; records concerning investigations of, or disciplinary actions related to, the work of behavior detection officers; and records related to allegations of racial, ethnic, religious, or national origin profiling related to behavior detection activities.

There is obvious appeal to some kind of seemingly rational and non-discriminatory process to whittle down the number of people who are subjected to more extensive scrutiny, particularly whenever the targets of such scrutiny happen to be young children or elderly women. Various law enforcement agencies have used profiles over the years in an attempt to detect human smugglers at the border, car thieves and sex abusers among others. Perhaps the best known profile is that of the drug courier, in which factors such as a traveler’s paying for an airplane ticket in cash, flying to a “source city” where narcotics are smuggled into the country, carrying little or no luggage and using an unusual travel itinerary give rise to a suspicion that the person is a drug smuggler. In United States v. Sokolow, the Supreme Court gave at least tacit acceptance to the use of profiling as an investigative tool insofar as the relevant profile factors are considered individually (as opposed to their merely being profile factors).

Of course, even seemingly race neutral profiles can be administered in discriminatory ways. Sixth Circuit Judge Damon Keith has argued as much about the Drug Enforcement Agency’s use of the drug courier profile. The New York Times, among other media outlets, has reported that the TSA has been “targeting not only Middle Easterners but also blacks, Hispanics and other minorities.”

The ACLU’s FOIA lawsuit seeks information relevant to two potential challenges to the TSA’s behavior detection programs: first, whether they are targeting minorities disproportionately, and second, whether they are effective at all even if used in non-discriminatory ways. Much has been written about the problems with racial profiling such as Randall Kennedy’s Race, Crime, and the Law, so I will focus on the second issue, other than to note that information responsive to the ACLU’s FOIA request may yield evidence to overcome the typical “Catch-22” that confronts plaintiffs raising selective enforcement claims.

Does Profiling Work?

The ACLU and other critics contend that the TSA has not identified a single airplane-bound terrorist through its behavioral detection program, which suggests that the program is both ineffective and burdensome. But this is quite a difficult standard to meet, considering that terrorism is (fortunately) an extremely low-incidence event. Since 9/11, there have been two attempted acts of terrorism against US-bound flights, both of which were stopped by alert passengers. Neither of those flights originated within the US, so the failure to detect either “shoe bomber” Richard Reid [PDF] (who departed from Paris) or “underwear bomber” Umar Farouk Abdulmutallab [PDF] (who departed from Amsterdam) cannot be blamed on TSA. Of course, it may be the case that terrorism against US flights is sufficiently difficult now given the post-9/11 precautions (e.g., hardened cockpit doors, millimeter wave scanners for passengers, computer tomography X-ray scanners for luggage, etc.) that behavioral profiling is not needed. But that is a different contention from arguing that profiling is ineffective.

Consider that on September 11, 2001, the Federal Bureau of Investigation and the Federal Aviation Agency were using a computerized system known as CAPPS I (Computer Assisted Passenger Prescreening System) to identify airlines passengers whose bags should undergo additional screening for explosives. The focus was on explosives because of terrorist incidents such as the inflight bombing of Pan Am Flight 103 in 1988.

On that day, CAPPS I picked 10 of the nineteen 9/11 hijackers for additional screening: Wail al-Shehri, Satam al-Suqami and Waleed al-Shehri (Flight 11); Hani Hanjour, Khalid al-Mihdhar, Majed Moqed, Nawaf al-Hazmi and Salem al-Hazmi (Flight 77); and Ahmad al-Haznawi (Flight 93). On the other hand, CAPPS I picked none of the hijackers on Flight 175. Thus, CAPPS I was slightly greater than 50 percent accurate at identifying the 9/11 hijackers. Moreover, CAPPS I identified suspicious persons on three of the four hijacked planes, providing at least an opportunity to have unraveled 75 percent of the hijacking teams.

CAPPS I was relatively simplistic, checking passenger names against FBI and other watch lists (including the no-fly list) to generate a terrorism risk score. The Bush Administration’s proposed successor program, CAPPS II, was spiked by the TSA, and Congress blocked another proposed successor, Secure Flight. To be sure, none of these programs relied on behavioral detection by TSA (or equivalent) agents. Moreover, the watch lists themselves could be infected by biases in terms of who selected whom to add. In other words, if investigators believe that terrorists come only from Middle Eastern countries, then the only people on the watch list used by CAPPS I would be persons from Middle Eastern countries. That might result in the detection of potential terrorists from Middle Eastern countries, but it would miss individuals from other parts of the world.

This suggests that the ACLU’s FOIA request, if granted, may lead to the discovery of whether TSA has any blind spots in its behavioral detection programs that are leading to the allegedly discriminatory impact on minority travelers. It may also lead to the discovery of the underlying bases for the detection programs, which in turn might support civil rights lawsuits against them as unreasonable searches in violation of the Fourth Amendment.

If not behavioral profiling, then what?

We might look ahead at how TSA might respond if it is ordered to reply to the FOIA request and the resulting information confirms the ACLU’s criticism that the behavioral detection programs are ineffective. One possibility is that TSA would simply stop subjecting anyone to secondary screening (although such a decision might put more pressure on the federal government to increase surveillance measures in an effort to acquire actionable intelligence).

Another possibility, however, is that TSA will cease using any formal profiling program but will instead rely more on individual TSA agents’ intuition and awareness. Is there reason to believe that individual gut feelings will be any better at detecting potential terrorists than a behavioral detection program? Consider the following two pre-9/11 incidents:

On December 14, 1999, Port Angeles, Washington-based US Customs Agent Diana Dean stopped a visitor who had taken his car on the ferry from Vancouver, British Columbia, for additional customs screening because he was acting “hinky.” As a result, she asked him to complete a Customs Declaration Form, on which he gave a name that matched his Canadian driver’s license but not his passport. A subsequent search by another customs agent found that the car was packed with explosives. The driver, later identified as Ahmed Ressam, pleaded guilty to conspiring to attack the Los Angeles International Airport with a car bomb.

On August 4, 2001, Orlando-based Immigration and Naturalization Service inspector Jose Meléndez-Pérez interviewed Saudi Arabian citizen Mohammed al Qahtani because al Qahtani’s immigration forms were completed incorrectly. Meléndez-Pérez felt that al Qahtani’s demeanor was evasive and that his responses were problematic in that he had limited assets, no return ticket and no place to stay. Meléndez-Pérez recommended denying al Qahtani entry, and the man was sent back to Saudi Arabia. He was later captured in Tora Bora, Afghanistan, and suspected of being the missing twentieth hijacker. (Three of the four hijacking teams consisted of two pilots and three “muscle,” while Flight 93 had two pilots and two muscle.)

Both Dean and Meléndez-Pérez received accolades for their actions (post-9/11 in Meléndez-Pérez’s case). Yet, Dean has stated that she acted on “gut instincts.” As Meléndez-Pérez has explained, “The bottom line is: He gave me the creeps.” Shifting toward an approach of individual gut instincts and perceptions of “the creeps,” even if successful in those two instances, seems more likely to exacerbate the problems posed by formal profiling programs than to alleviate them.

Why is it so hard to balance terrorist detection with privacy rights?

US airlines have estimated that there will be 2.2 million passengers every day in March and April 2015. Since 9/11, there have been fewer than five terrorism attempts against planes: the shoe bomber, the underwear bomber, the London liquid explosives plot and a cargo plane plot. The degree of sensitivity required to detect such astronomically rare events, in the absence of actionable intelligence, without imposing upon a significant number of other persons measurable hardship is most likely beyond our present capabilities, absent some sort of super advanced real-time scanning operation like the one depicted in the science fiction movie Total Recall [Video].This isn’t to say that the ACLU’s FOIA lawsuit is therefore without purpose. Estimates of the frequency of false positives may be useful for policy discussions about whether that frequency is low enough to justify the particular detection program, or too high to be considered reasonable. But successful pursuit of the FOIA lawsuit is only the beginning, not the end, of the discussion of appropriate screening procedures.

Tung Yin is a professor of law at Lewis & Clark Law School. His scholarly work focuses on domestic legal issues that have arisen out of the US military and prosecutorial responses to the 9/11 attacks.

Suggested Citation: Tung Yin, Security Screening: Science or Sorcery?, JURIST – Academic Commentary, April 13, 2015,

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