Changes in Airport Passenger Screening Technologies and Procedures: Frequently Asked Questions

Changes in Airport Passenger Screening Technologies and Procedures: Frequently Asked Questions

Changes in Airport Passenger Screening
Technologies and Procedures:
Frequently Asked Questions
Bart Elias
Specialist in Aviation Policy
January 26, 2011
Congressional Research Service
7-5700
www.crs.gov
R41502
CRS Report for Congress
P
repared for Members and Committees of Congress

Changes in Airport Passenger Screening Technologies and Procedures

Contents
Introduction ................................................................................................................................ 1
What Changes Have Been Made?................................................................................................ 1
What Prompted These Changes? ................................................................................................. 1
What Is Advanced Imaging Technology and How Is It Being Used? ............................................ 2
What Is the Funding for AIT?...................................................................................................... 2
How and Where Is AIT Being Deployed? .................................................................................... 3
Where Else Is AIT Being Deployed? ........................................................................................... 3
Is AIT Effective?......................................................................................................................... 3
Is AIT Efficient? ......................................................................................................................... 4
What Specific Changes Have Been Made to Pat-Down Procedures?............................................ 5
Why Do the New Screening Procedures Raise Privacy Concerns? ............................................... 5
What Has Been Done to Allay Privacy Concerns? ....................................................................... 6
What Concerns Have Been Raised Regarding Religious or Cultural Sensitivities? ....................... 7
Does WBI Have Potential Human Health Effects?....................................................................... 7
What Screening Options Do Passengers Have?............................................................................ 8
What If Passengers Have a Specific Complaint About Screening? ............................................... 9
What Alternative Screening Techniques Are Available? ............................................................... 9
Have These Issues Been Addressed in Legislation? ................................................................... 10

Contacts
Author Contact Information ...................................................................................................... 11

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Changes in Airport Passenger Screening Technologies and Procedures

Introduction
In the autumn of 2010, the Transportation Security Administration (TSA) began deploying new
technologies and procedures for screening passengers at airport checkpoints. Reports of negative
public reaction to some of these changes have prompted intense congressional interest in TSA
passenger screening. This report addresses some of these concerns.
What Changes Have Been Made?
During 2010, TSA introduced whole body imaging (WBI) systems at airport checkpoints around
the United States. Previously, the systems were used only on a trial basis at a small number of
airports. They are now in use as a primary screening method at most busy passenger airports.
These systems, which TSA refers to as advanced imaging technology (AIT) systems, capture an
image of what lies underneath an individual’s clothing. Critics have referred to this as a “virtual
strip search.”1 If an individual considers this screening method too invasive or revealing or
prefers not to undergo AIT imaging for any other reason, TSA provides the option of submitting
to a pat-down search instead.
In response to aircraft bombing attempts and intelligence regarding terrorist explosives
concealment methods, TSA also has changed pat-down procedures to more thoroughly inspect
individuals for concealed items. The use of pat-down procedures has also become more frequent,
including searches conducted at gates immediately prior to boarding.
What Prompted These Changes?
Because of improvements to prevent airline hijackings made since 9/11, TSA now regards
explosives as the main threat to passenger airliners. The inability of walk-through metal detectors
to screen for explosives has been seen as a critical weakness in aviation security.
In 2004, the 9/11 Commission recommended that TSA give priority attention to implementing
technologies and procedures for screening passengers for explosives.2 The bombing of two
Russian airliners in August 2004, shortly after the release of the commission’s report, focused
considerable attention on this issue. Based on the 9/11 Commission’s recommendation, Congress
included provisions in the Intelligence Reform and Terrorism Prevention Act of 2004 (P.L. 108-
458) directing TSA to improve checkpoint screening technologies capable of detecting
explosives. TSA initially tested walkthrough portals that analyze samples of air passed over
individuals for traces of explosives. However, TSA considered these systems to be unreliable in
the airport environment and has more recently focused on WBI technologies.

1 For example, Jessica Ravitz, “Airport Security Bares All, Or Does It,” CNN.com/travel, May 18, 2009, available at
http://edition.cnn.com/2009/TRAVEL/05/18/airport.security.body.scans/?iref=mpstoryview.
2 National Commission on Terrorist Attacks Upon the United States. The 9/11 Commission Report, New York, NY: W.
W. Norton & Co., 2004.
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On December 25, 2009, an air passenger, Umar Farouk Abdulmutallab, attempted to ignite an
explosive device concealed in his underwear while on board a Detroit-bound commercial flight
from Amsterdam. This incident prompted additional changes to security screening procedures. In
addition to increasing its reliance on WBI as a primary screening technology, TSA has changed
its pat-down search procedures and increased the use of pat-down searches.
What Is Advanced Imaging Technology and How Is
It Being Used?
AIT systems are commonly referred to as whole body imaging systems or full-body scanners. The
technology does not specifically identify explosives, but can reveal concealed items that would
not be detected by walkthrough metal detectors, including explosives and non-metallic weapons.
If a concealed item is detected, TSA procedures require that screeners3 use additional inspection
methods to determine whether the item is a threat. These methods may include pat-downs, visual
inspection, or swabbing an individual’s skin and/or clothing to obtain a sample to analyze for
traces of explosives.
TSA has approved two AIT systems for operational use. One of those systems, the Rapiscan
Secure 1000, uses a technology called X-ray backscatter; the other, the L-3 ProVision, uses
millimeter wave imaging. Most fielded versions of these systems require the individual to assume
only one pose to generate images, allowing screeners to detect any concealed items the person
may be carrying. The ProVision system acquires multiple images whereas the Rapiscan Secure
1000 takes two images: a front view and a back view. A third system, the AS&E Smartcheck Z
Backscatter system, was previously tested at airports but has not been evaluated by TSA for large-
scale acquisition. One disadvantage of this system is that it requires the individual to stand in two
poses to render front-view and rear-view images. Other vendors manufacture whole-body
imaging systems using a variety of technologies, some of which are being evaluated to determine
if they meet TSA’s operational performance requirements.
What Is the Funding for AIT?
In FY2008, Congress established an airport checkpoint screening fund providing $250 million for
advanced checkpoint technologies (see P.L. 110-53). Additional funding was provided in the
regular FY2009 appropriations. The American Recovery and Reinvestment Act (ARRA) of 2009
(P.L. 111-5) included $1 billion for aviation security, of which $300 million went to accelerate the
acquisition and deployment of whole-body imaging systems. In FY2010, $117 million was
appropriated and the President’s budget request for FY2011 sought $344 million for checkpoint
technologies. Although these amounts also fund the purchase of next-generation X-ray equipment
for screening carry-on bags, AIT accounts for a large share of checkpoint technology acquisition.

3 TSA employees perform passenger and baggage screening functions at most airports. At some airports, these
functions are performed by employees of private companies subject to TSA oversight.
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How and Where Is AIT Being Deployed?
In October 2007, TSA began its initial field test of WBI screening at Phoenix Sky Harbor
Airport.4 In that trial, an X-ray backscatter system was offered as an alterative to pat-down
searches for passengers selected for additional secondary screening. More extensive testing at
various airports using both X-ray backscatter and millimeter wave systems commenced in 2008.
Over the past two years, TSA has significantly expanded its deployment of AIT systems. As of
January 2011, 486 AIT units had been deployed to 78 airports. The President’s budget request for
FY2011 sought funding for 503 additional units, to bring the nationwide total to roughly 1,000.
While it is unclear what the nationwide mix of systems will be once all systems are deployed,
individual airports appear to be receiving either millimeter wave or backscatter systems, but not
both. Presently, the systems are not used in all screening lanes. System-wide, there are more than
750 screening checkpoints and over 2,000 screening lanes across 450 airports in the United
States. TSA’s goal is to have 1,800 units deployed across the country by the end of FY2014. It
refers to this number as its full operating capability for AIT. An updated list of airports with AIT
technology is available on TSA’s website.5
Where Else Is AIT Being Deployed?
AIT systems are in operational use at a few foreign airports, primarily in Europe. In many cases,
they are used solely to screen passengers traveling on U.S.-bound flights. Canada uses the
systems in selected airports to screen both domestic and international passengers. The procedures
and privacy protections vary from country to country. In addition to aviation security
applications, AIT is being used at state and federal courthouses, correctional institutions,
embassies, and border crossings, and by the Department of Defense, mostly overseas.
Is AIT Effective?
TSA generally regards AIT as an effective solution for detecting concealed threats carried by
passengers. Its heavy investments in the technology indicate TSA’s commitment to making AIT a
central part of its strategy for detecting explosives at passenger checkpoints. TSA, in cooperation
with the Department of Homeland Security’s Transportation Security Laboratory, conducts
laboratory and operational testing and evaluation of screening technologies. In the case of AIT,
these methods include extensive performance studies using trained human observers under
simulated and actual operational conditions. Approved AIT systems in use at airports have met
TSA’s operational requirements for threat detection. For security reasons, TSA’s specific
standards cannot be divulged publicly, although TSA officials have said that AIT performance
was comparable to pat-down searches in operational tests.6

4 John Lettice, “‘Virtual Strip Search’ Arrives at JFK and LAX,” The Register (UK), April 22, 2008.
5 http://www.tsa.gov/approach/tech/ait/faqs.shtm.
6 U.S. Government Accountability Office, TSA Is Increasing Procurement and Deployment of the Advanced Imaging
Technology, but Challenges to This Effort and Other Areas of Aviation Security Remain, GAO-10-484T, March 17,
2010.
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Experts are divided about the effectiveness of AIT systems, and it remains unclear whether a WBI
scan would have detected the explosives used in the 2009 Christmas Day bombing attempt.7 Of
particular concern is the potential that terrorists could use certain concealment tactics to evade
detection by AIT. Modeling by independent researchers, based on publicly available performance
estimates, found that certain concealed items—including types of explosives used in past
terrorism attempts targeting aircraft—would be difficult, if not impossible, to detect using X-ray
backscatter systems at current radiation exposure levels. They concluded that “[e]ven if exposure
were to be increased significantly, normal anatomy would make a dangerous amount of plastic
explosives with tapered edges difficult if not impossible to detect.”8 There is a separate debate as
to whether the money appropriated for WBI would be better spent on intelligence-gathering.9
Is AIT Efficient?
TSA procedures for screening at walkthrough metal detectors can be cumbersome. Passengers are
typically instructed to remove all metallic items, including cell phones, keys, coins, and
sometimes even jewelry and belts with metal buckles. Since a December 2001 shoe-bombing
attempt, passengers have been required to remove their shoes and place them with other carry-on
items for X-ray screening. When passengers forget to remove metallic objects, the system can be
slowed by nuisance alarms that must be resolved through secondary screening.
The procedures for AIT, as currently implemented, do not eliminate any of these requirements
and impose additional requirements to remove non-metallic items, such as wallets, from pockets
to minimize false positive determinations. Also, unlike metal detectors that passengers can move
through quickly, WBI systems require passengers to assume a pose in front of the imager for
several seconds. Since the systems are new and passengers are largely unfamiliar with them, TSA
screeners must provide detailed instructions, adding to the time required to screen a passenger. If
large numbers of passengers are required to undergo AIT screening, longer security lines could
result. Additional delays could prompt complaints even from passengers who do not object to the
screening methods. TSA points out, however, that AIT screening is much quicker and more
efficient than a pat-down search. TSA also contends that AIT does not significantly impact
checkpoint efficiency at current utilization levels because AIT screening is typically faster than
screening of carry-on items.
TSA could minimize delays by using WBI only at times when security lines are short. However,
such a strategy could lead to vulnerabilities if terrorists carrying explosives could time their entry
into a screening lane to minimize the probability that they would undergo WBI screening.

7 U.S. Government Accountability Office, Better Use of Terrorist Watchlist Information and Improvements in
Deployment of Passenger Checkpoint Technologies Could Further Strengthen Security, GAO-10-401T, January 27,
2010.
8 Leon Kaufman and Joseph W. Carlson, “An Evaluation of Airport X-ray Backscatter Units Based on Imaging
Characteristics,” Journal of Transportation Security, published online November 26, 2010, available at
http://www.springerlink.com/content/g6620thk08679160/.
9 Jessica Ravitz, “Airport Security Bares All, Or Does It?,” CNN.com/travel, May 18, 2009, available at
http://edition.cnn.com/2009/TRAVEL/05/18/airport.security.body.scans/?iref=mpstoryview.
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What Specific Changes Have Been Made to Pat-
Down Procedures?
In October 2010, TSA announced revisions to its pat-down procedures to more thoroughly
examine individuals for concealed threats.10 Previously, TSA procedures called for screeners to
use only the backs of their hands when inspecting sensitive areas. The new procedures involve
using the front of the hand to search for concealed items and more detailed tactile inspection of
areas higher on the thigh and in the groin area. The procedures routinely involve touching of
buttocks and genitals.11 As with prior procedures, all pat-downs are conducted by a same-sex
screener, and passengers may opt for a screening in a private area. In congressional testimony on
November 17, 2010, TSA Administrator John Pistole conceded that the methods are clearly more
invasive than prior methods, but defended them as necessary to detect concealed threats and
indicated that he has no intention of modifying the new techniques.
Why Do the New Screening Procedures Raise
Privacy Concerns?
Polling data indicate that about 75% to 80% of Americans support the use of AIT at airport
checkpoints.12 However, AIT has met with objections from groups such as the American Civil
Liberties Union, which has urged Congress to ban the use of whole body imaging technologies as
a method for primary screening on the basis that “[p]assengers expect privacy underneath their
clothing and should not be required to display highly personal details of their bodies.”13 In the
United Kingdom, questions have been raised about whether whole body imaging of children
violates child pornography laws.14 So far, this particular aspect of privacy has not been the subject
of detailed policy discussion in the United States, and children are not categorically excluded
from WBI screening.
With regard to pat-down procedures, TSA has faced allegations of groping, singling out female
passengers, and other abuses. In 2005, an extensive investigation by the Department of Homeland
Security Office of Inspector General found that TSA adequately advised passengers of their rights
under the pat-down procedures, and appropriately accommodated those rights. It also found that
TSA’s screener training for pat-down searches was adequate and that pat-downs were performed
on proportionate numbers of males and females.15 TSA logs and investigates complaints and
tracks trends in complaint data to identify areas of concern and take remedial action as needed.

10 Transportation Security Administration, TSA Statement on New Pat-down Procedures, October 28, 2010.
11 Derek Kravitz, “New Searches Too Personal for Some Air Travelers,” Washington Post, November 13, 2010.
12 See AIT polls at http://www.tsa.gov/approach/tech/ait/reading.shtm.
13 Statement of Timothy D. Sparapani, ACLU Legislative Counsel, Before the Senate Committee on Commerce,
Science, and Technology, Regarding the U.S. Transportation Security Administration’s Physical Screening of Airline
Passengers and Related Cargo Screening, April 4, 2006.
14 Alan Travis, “New Scanners Break Child Porn Laws,” Guardian (UK), January 4, 2010.
15 Department of Homeland Security, Office of Inspector General, Review and Audit of the Transportation Security
Administration’s Use of Pat-Downs in Screening Procedures (REDACTED), November 2005, OIG-06-10.
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Nevertheless, TSA’s new, more thorough pat-down procedures have brought complaints, as
similar touching could constitute sexual assault in other circumstances.
Privacy arguments have been made about other airport screening procedures in the past, to no
avail. Courts characterize a routine search conducted at an airport security checkpoint as a
warrantless search, generally not subject to the constitutional prohibition against “unreasonable
searches and seizures” by the federal government. Such a warrantless search, also known as an
administrative search, has been found acceptable if it is “no more intrusive or intensive than
necessary, in light of current technology, to detect weapons or explosives,” is confined to that
purpose, and if individuals may avoid the search by electing not to fly.16 In more recent case law,
the 9th Circuit Court of Appeals ruled that airport searches of passengers are reasonable and do
not require consent, as “… requiring that a potential passenger be allowed to revoke consent to an
ongoing airport security search makes little sense in a post-9/11 world. Such a rule would afford
terrorists multiple opportunities to attempt to penetrate airport security by ‘electing not to fly’ on
the cusp of detection until a vulnerable portal is found.”17 The Supreme Court, however, has not
specifically ruled that airport screening searches are a constitutionally reasonable form of
administrative search. More specific policy and legal analysis in the current context may be
needed to address whether the new procedures are no more intrusive or intensive than necessary.
What Has Been Done to Allay Privacy Concerns?
TSA has long been aware of the potential privacy concerns regarding WBI systems. To allay
some of these concerns, the millimeter wave systems used by TSA apply privacy filters that blur
facial features. X-ray backscatter systems currently deployed use computer algorithms to render a
“chalk outline” sketch of the individual and discernible concealed items.
TSA also has implemented procedures for remote viewing of WBI images. Under these
procedures, the screener viewing the images cannot see the individual that was imaged and views
the images in an enclosed space that is not in public view. Also, the systems in use by TSA have
no capacity to store or transmit images, and screeners are prohibited from having any cameras or
recording devices in their possession while viewing WBI images. Under TSA procedures, images
are immediately deleted after the individual has been screened.
Proposed enhancements to further address the privacy issue involve technical advances. With
fully or semi-automated threat detection capabilities, screeners might not have to view images at
all, or might only have to view certain portions of an image to respond to automatically detected
threats and anomalies. Automated detection capabilities are being currently being tested in the
laboratory, and software modifications to existing AIT systems may be field-tested later this year.
These modifications would display images of generic figures with boxes alerting screeners to
potential threats rather than displaying actual body images.18 Alternatively, additional distortion

16 United States v. Davis, 482 F.2d 893-908 (9th Cir. 1973).
17 United States v. Aukai, 497 F.3d 955-963 (9th Cir. 2007), p. 959.
18 John Hughes, “U.S. Airports May Soon Test Body Scanner With Privacy Upgrades, TSA Says,” Bloomberg News,
January 13, 2011.
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of the images to make them less revealing without compromising their ability to detect potentially
dangerous concealed objects has been suggested, but has not been evaluated by TSA.19
What Concerns Have Been Raised Regarding
Religious or Cultural Sensitivities?
TSA does not exempt individuals from screening procedures on the basis of religion or culture.
Therefore, an individual must agree to either WBI screening or a pat-down search, even if these
methods conflict with religious beliefs or cultural practices.
TSA has particular security concerns regarding loose-fitting clothing and headwear that could
potentially conceal threats including explosives. Members of certain religious groups, including
some Muslims, and certain cultures, including some African cultures, often wear loose fitting
clothing. Additionally, certain religions and cultures sometimes require individuals to wear head
coverings in public. Examples include hijabs worn by some Muslim women, yarmulkes worn by
some Jewish men, and turbans worn by members of various religious groups.
TSA does not prohibit any individual from wearing loose-fitting clothing or head coverings when
passing through a screening checkpoint. However, TSA screeners may select individuals for
additional screening if they consider their clothing to be loose fitting enough or large enough to
conceal a prohibited threat item. Similarly, TSA screeners may require additional screening and
physical inspection of headwear. Because of these procedures, specific groups may believe that
they are being targeted for additional screening on the basis of ethnic or cultural identity rather
than on the basis of their loose-fitting clothing or headwear. Concerns may also arise during pat-
down searches if passengers object to touching by screeners on religious or cultural grounds.
Does WBI Have Potential Human Health Effects?
Potential human health concerns apply to one of the two WBI systems now used by TSA, X-ray
backscatter systems. TSA contends that the levels of ionizing radiation emitted by approved X-
ray backscatter systems are well below levels considered safe for human exposure. The radiation
exposure from a single X-ray backscatter image is said to be equivalent to the naturally occurring
radiation received during two minutes flying at altitude aboard a commercial airliner.20 Approved
backscatter systems have been evaluated by the Food and Drug Administration’s Center for
Devices and Radiological Health, the National Institute of Standards and Technology, and the
Johns Hopkins University Applied Physics Laboratory.
The controversy over exposure to X-ray backscatter persists. In April 2010, faculty members
from the University of California, San Francisco, including prominent researchers in
biochemistry, biophysics, X-ray imaging, and cancer research, expressed their concerns in a letter
to President Obama’s assistant for science and technology, John P. Holdren. They suggested that
while the radiation dose received from X-ray backscatter imaging would be safe if it were

19 Ashley Halsey III, “A Fix for TSA Scanning Worries?,” Washington Post, November 22, 2010.
20 http://www.tsa.gov/approach/tech/ait/faqs.shtm.
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distributed throughout the body, it is instead concentrated only on the skin and underlying tissue,
such that “the dose to the skin may be dangerously high.”21 The letter stated that older travelers
and those with compromised immune systems may be at particular risk; that some females may
be at higher risk of developing breast cancer; that the potential health effects on children,
adolescents, pregnant women, and fetuses have not been fully assessed; that the proximity of the
testicles to the skin raises concerns over possible sperm mutation; and that the effects on the
cornea and the thymus gland have not been determined. It also cautioned that a system
malfunction could potentially cause a very high radiation dose to be concentrated on a single spot.
TSA and the Food and Drug Administration provided a lengthy response to the letter, asserting
that the potential health risks from full-body screening using approved systems are minuscule,
and that extensive independent data confirm that the systems do not present significant risk to
public health.22
The millimeter wave systems used by TSA do not emit ionizing radiation, the type of radiation
usually considered to have sufficient energy to modify the molecular structure of cells, which has
been linked to various forms of cancer.23 They therefore have not raised the same health concerns.
What Screening Options Do Passengers Have?
Statutes require TSA to administer the screening of passengers and property entering security
controlled areas of airports. The statutes give TSA authority to define screening requirements
subject to certain criteria.24 Individuals entering security controlled areas without submitting to
applicable screening procedures may be subject to civil and criminal penalties.25
Under its screening procedures, TSA allows those individuals selected to undergo WBI screening
to instead opt to undergo a pat-down search. In some cases, passengers opting for WBI screening
during primary screening may subsequently be required to undergo a pat-down search if there are
anomalies in their images. For example, well-known humorist Dave Barry reported that he was
instructed to undergo secondary pat-down screening after being told he had a “blurred groin.”26
Once selected to undergo one of the enhanced screening methods, passengers are not given the
option of selecting screening using a walk-through metal detector. Under current TSA procedures,
once an individual has initiated the screening process, he or she must complete it. This means that
if selected for WBI or a pat-down, the individual must undergo one of these two options. Also, if
the individual is ordered to undergo a pat-down secondary screening to resolve a metal detector

21 John W. Sedat, Ph.D., Marc Shuman, M.D., David Agard, Ph.D., and Robert Stroud, Ph.D., Letter to Dr. John P.
Holdren, Assistant to the President for Science and Technology, April 6, 2010, available at http://www.whitehouse.gov/
sites/default/files/microsites/ostp/ucsf-jph-letter.pdf.
22 Department of Health and Human Services, Food and Drug Administration, Center For Devices and Radiological
Health. Letter to Dr. John P. Holdren from John L. McCrohan, Deputy Director for Technical and Radiological
Initiatives, and Karen R. Shelton Waters, Deputy Assistant Administrator/ Chief Administrative Officer, Transportation
Security Administration, October 12, 2010, available at http://www.whitehouse.gov/sites/default/files/microsites/ostp/
fda-backscatter-response.pdf.
23 American Cancer Society, Radiation Exposure and Cancer, available at http://www.cancer.org/Cancer/
CancerCauses/OtherCarcinogens/MedicalTreatments/radiation-exposure-and-cancer.
24 See 49 U.S.C. § 44901.
25 See 49 U.S.C. § 46314.
26 “Humorist Dave Barry and His TSA Pat-Down,” All Things Considered, NPR, November 19, 2010.
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alarm or WBI image anomaly, then the individual must comply. The individual cannot simply exit
from the screening area and then enter a different security lane in an attempt to avoid WBI
screening or a pat-down search. If, after purchasing a ticket, a passenger decides not to fly
because of these security requirements, any refund would be handled by the airline, subject to the
specific terms of the contract of carriage between the passenger and the airline. This situation
poses a considerable dilemma for individuals who have purchased nonrefundable tickets but are
uncomfortable with both WBI screening and pat-down searches.
What If Passengers Have a Specific Complaint
About Screening?
TSA encourages passengers to immediately notify a TSA supervisor or customer service manager
to report complaints. The TSA Contact Center also provides a toll-free number (866-289-9673)
and an online complaint form.27
If passengers believe their rights have been violated, TSA’s Office of Civil Rights and Liberties is
internally responsible for investigating claims of violations during checkpoint screening. Such
claims may include violations of civil liberties, such as harassment, or violations of civil rights,
such as discrimination on the basis of race, ethnicity, age, religion, gender, disability, or sexual
orientation. After traveling, a passenger may file a formal complaint describing an incident with
the TSA Office of Civil Rights and Liberties External Compliance Division.28 Complaints may
also be filed with the parent Department of Homeland Security’s Office for Civil Rights and Civil
Liberties.29 TSA indicates that it will process external complaints filed up to 180 days after an
alleged incident, but notes that delays in filing a complaint may significantly limit its ability to
conduct a fact-finding investigation. Based on its investigation, TSA may take disciplinary action
or other remedial action, such as additional screener training.
What Alternative Screening Techniques Are
Available?
The primary alternative to WBI for explosives screening is explosives trace detection, particularly
walkthrough explosives trace detection portals. TSA conducted field tests of such technology in
2004. However, citing reliability problems, TSA suspended further deployment, and it has not
sought to acquire additional trace portal systems.
Canine teams offer another possible option for explosives detection. TSA, in coordination with
state and local law enforcement, has, in total, more than 600 explosives detection canine teams,
about 80% of which focus on aviation and air cargo screening. It plans to field more than 1,000
teams, with 90% focused on aviation, by the end of FY2011. However, these teams are not used

27 See http://www.tsa.gov/contact/index.shtm.
28 Transportation Security Administration, Office of Civil Rights and Liberties (TSA-6), External Compliance Division,
601 S. 12th Street , Arlington, VA 20598; e-mail: TSA.OCR-ExternalCompliance@dhs.gov.
29 Department of Homeland Security, Office for Civil Rights and Civil Liberties, Review and Compliance, 245 Murray
Lane, SW, Building 410, Mail Stop #0190, Washington, DC 20528; e-mail: civil.liberties@dhs.gov.
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routinely for screening passengers and spend most of their time inspecting cargo and baggage and
patrolling airport terminals. Although canine teams may be less objectionable to some individuals
uncomfortable with WBI and pat-down searches, some individuals have a fear of or allergies to
dogs. There also may be religious and cultural sensitivities regarding the use of dogs to search
individuals. Large numbers of canine teams would be needed to make this a viable option for
screening large numbers of air travelers. Further research may be needed to determine if canines
provide an adequate level of screening. One complication is that dogs trained to sniff out
explosives would not be capable of detecting other threats, such as nonmetallic weapons.
Have These Issues Been Addressed in Legislation?
In 2009, Representative Chaffetz introduced the Aircraft Passenger Whole-Body Imaging
Limitations Act (H.R. 2027, 111th Congress), which would have prohibited the use of WBI for
routine screening and would have assured passengers the option to select a pat-down search. The
bill would also have prohibited the storage, transfer, sharing, or copying of any image of a
passenger generated by a WBI screening system. This proposal was offered as an amendment
(H.Amdt. 172) to the Transportation Security Administration Authorization Act (H.R. 2200) and
was included in the version of that bill passed by the House on June 4, 2009 (see Section 215).
In contrast, Senator Bennett offered the Securing Aircraft From Explosives Responsibly:
Advanced Imaging Recognition (SAFER AIR) Act of 2010 (S. 3536, 111th Congress) on June 24,
2010. That measure called for the expeditious deployment and use of AIT and other advanced
technologies for primary screening of aircraft passengers, and would have given passengers the
option of passing through a metal detector and undergoing pat-down screening instead of
undergoing AIT screening. Although S. 3536 would have required AIT to be used as a primary
screening method, whereas H.R. 2027 and H.R. 2200 would have prohibited it from use as a
primary screening method, the bills had in common several concepts for protecting privacy. Many
of these provisions paralleled current TSA practices.
On November 17, 2010, Representative Paul introduced the American Traveler Dignity Act of
2010 (H.R. 6416, 111th Congress). This bill would have barred TSA, TSA screeners, private
airport security screeners, or others involved in the screening process to claim immunity from
prosecution in a criminal or civil proceeding arising as the result of whole-body screening or a
pat-down search. Representative Paul, in discussing the legislative proposal, asserted that TSA
screeners should not be immune from laws pertaining to sexual assault; child pornography; and
the endangering of others through the use of radiation-emitting machinery.30

30 Representative Ron Paul, Introducing the American Traveler Dignity Act, available at http://paul.house.gov/
index.php?option=com_content&task=view&id=1796&Itemid=60.
Congressional Research Service
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Changes in Airport Passenger Screening Technologies and Procedures

Author Contact Information

Bart Elias

Specialist in Aviation Policy
belias@crs.loc.gov, 7-7771

Congressional Research Service
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