Public Transportation Passenger Security Inspections: A Guide for Policy Decision Makers (2007)

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15 Cities and transit systems outside the United States have had considerably more experience than U.S. cities and transit systems with terrorism and have already implemented many security measures, including CCTVs and smart cameras. PSIs and other security measures—such as video surveillance of public locations—are more acceptable to the populations and customers of systems outside the United States than they are to populations and customers of systems in the United States. In Israel, PSIs using behavioral assessments and technologies, such as handheld metal detectors and explosives detection portals, occur on a daily basis. PSIs occur not only at Israeli airports but also at transit terminals and bus and train stations. In fact, these security inspections have been integrated into daily life; they occur at shopping malls, supermarkets, office buildings, and other public places. This integration of PSIs into daily life in Israel has made implementation of PSIs in its transit systems easier and more amenable to the public. In Europe, Eurostart—a high-speed train connecting London to Paris, Brussels, and other cities through the channel tunnel— has implemented an airport-style screening system. Passengers are required to arrive about 45 minutes ahead of their sched- uled departures and must go through a security checkpoint that uses magnetometer walk-through portals. In the United States, Boston was the first city to conduct PSIs. In July 2004, during the Democratic National Convention, MBTA transit police conducted random baggage and identifi- cation checks at major rail stations in response to increased security concerns following the Madrid commuter rail attacks earlier that year. Behavior pattern recognition training was provided to the MBTA transit police by state police officers sta- tioned at Logan airport so that suspicious behavior could be identified.19 In July 2005, in response to the London transit bombings, the transit agencies in the New York/New Jersey metropolitan area began random inspections of bags and other objects, primarily at major transit hubs. Initially, these inspec- tions were limited to manual and visual checks; however, in 2006, the inspections were expanded to include the use of elec- tronic trace detection equipment.20 Canine inspection is also used at one agency for both primary and secondary inspections at random checkpoints. Public advocacy groups, civil liberties groups, and other organizations in both New York and Boston have protested the PSIs adopted in response to transit bombings overseas and have brought legal action against the agencies. However, the courts have upheld the right of the agencies in conduct- ing them.21 As evidenced by the transit agency interview results, agencies in other metropolitan areas conduct PSIs using canines because canine inspection is viewed as less intrusive than manual, visual, and electronic inspection methods. Boston has also been using behavioral assessment to con- duct PSIs within its transit system and at its airports. Because behavioral assessment has been highly successful in airline passenger screening in Israel, it has been gaining interest in the United States and is being introduced into transit systems in other cities. PSI methods can be used for primary and/or secondary screening. Certain methods, such as explosives detection portals, would be more likely to be used for primary inspec- tions than for secondary inspections. Other methods, such as canine inspections, can be used for either. The randomness of PSI location is important because inspection of 100% of passengers is not feasible for most transit systems. Randomness provides legal, operational, and security C H A P T E R 2 Passenger Security Inspection (PSI) Methods 19 M. Daniel, “MBTA set to begin passenger ID stops,” Boston.com, May 22, 2004. http://www.boston.com/news/local/articles/2004/05/22/mbta_set_to_ begin_passenger_id_stops/. 20 A summary of the New York and New Jersey programs can be found in B. M. Jenkins and B. R. Butterworth, Selective Screening of Rail Passengers, MTI Report 06-07 (San Jose, CA: Mineta Transportation Institute, February 2007), 36–37. 21 J. Preston, “Police Searches in the Subways Are Upheld,” New York Times, December 3, 2005.

benefits. Legal benefits include a diminished probability of allegations of racial/ethnic profiling, operational benefits include a decreased probability of queues occurring, and secu- rity benefits include the deterrence effect of randomness. PSIs Using Manual or Visual Inspection Methods PSIs using manual or visual inspection methods involve the random selection of transit passengers and inspection of the contents of their bags or other objects in their possession. In a manual inspection, an officer opens a passenger’s bag, inspects the contents, and may move the items within the bag to obtain a better view of the contents. In a visual inspection, the passenger opens his or her bag and the officer observes the contents but does not touch them. In order to minimize the invasion of passengers’ privacy, officers may be trained to hide the contents of a bag from other passengers and not to read letters or other documents within the bag. Further details of these procedures are described in the summary of the transit agency interviews in Chapter 3. PSI Technologies PSI technologies have a long history of use in the U.S. aviation industry for passenger and baggage screening. Recently, use of PSI technologies has been initiated in port security to screen cargo. Although these technologies are being explored by, and some have been tested on, U.S. pub- lic transportation systems, they have not been deployed for 100% passenger inspections because of a number of issues. While some of these issues, such as privacy, appear to over- lap with issues that arise in passenger screening for aviation, public transit is different in many aspects from aviation and other industries. The two categories of explosives detection technologies are bulk detection and trace detection technologies. It should be noted that detection systems using these technologies still require human judgment and intervention to a greater or lesser extent. When the system issues an alarm, identification of the source of the alarm is needed. This is accomplished through secondary screening. Bulk detection devices detect explosives by imaging the baggage contents and locating shapes of the explosive charge itself. Bulk detection devices can also identify any detonators, timers, or connecting wires. Bulk detection devices—specifi- cally, certified Explosives Detection Systems (EDSs)—can also identify explosives in a direct manner by detecting the chemical or dielectric properties of the material. The key cat- egories of bulk detection technologies are X-rays (including computer tomography for the current generation of EDSs), neutrons, electromagnetic imaging, and gamma rays. Trace detection focuses on vapors or particles given off by explosives. These vapors or particles may be found on the sur- face of items that have come in contact with explosives or that have been in close proximity to explosives. These items include luggage, backpacks, documents such as tickets and boarding passes, and skin. Trace detection can be electronic/chemical or optical, or it can use biosensors. The large investment in airport security and the attention given to the screeners and screening process suggest that a great deal of time, effort, and resources would be needed for transit agencies to develop and implement a robust screening system, especially when the system requires human interven- tion. A GAO report on screener training and performance measurement concludes that despite screener training and the resources expended on the screening process, “overall, weaknesses and vulnerabilities continue to exist in the pas- senger and checked baggage screening systems at airports of all sizes, at airports with federal screeners, and at airports with private-sector screeners.”22 This finding, combined with the perspective of many transit agencies that airport equipment would be operationally and financially infeasible for them, makes it unlikely that transit agencies, especially non-ferry agencies, will implement airport-style 100% passenger inspection systems. A description of the TSA airport screen- ing methodology and training program is provided in Appendix C of this report.23 Detection equipment that does not affect operations and cause customer delays is highly desirable. For instance, sensors that are embedded in ticketing machines or fare collection devices are being reviewed by DHS, and plans are being made for testing them. These types of technologies, as well as environmental monitoring technologies, are particu- larly appealing for use at high ridership transit environments such as major transit hubs. PSI technologies range from large scanners to portable and handheld devices. In terms of public perception and privacy for passenger screening, devices such as walk-through portals are generally considered less intrusive than handheld wands or manual searches because physical contact between the detector and the passenger does not occur. Standoff tech- nologies are typically even less intrusive. Standoff detection is defined by the Committee on the Review of Existing and Potential Standoff Explosives Detection Techniques of the National Research Council as follows: 16 22 GAO, Aviation Security Screener Training and Performance Measurement Strengthened, but More Work Remains (Report to the Chairman, Subcommittee on Aviation, Committee on Transportation and Infrastructure, House of Rep- resentatives), GAO-05-457 (Washington, DC: GAO, May 2005). 23 For further reading on robust screening, see B. M. Jenkins and B. R. Butterworth, Selective Screening of Rail Passengers, MTI Report 06-07 (San Jose, CA: Mineta Transportation Institute, February 2007).

Standoff explosive detection involves passive and active methods for sensing the presence of explosive devices when vital assets and those individuals monitoring, operating, and responding to the means of detection are physically separated from the explosive device. The physical separation should put the individuals and vital assets outside the zone of severe damage from a potential detonation of the device.24 However, one standoff technology, the X-ray backscatter technology, “sees” through clothing and has caused related privacy concerns. The different PSI technologies have been categorized as people screening, baggage screening, and vehicle screening and are summarized below. People Screening Technology Portable Devices. Portable devices tend to be the size of a large suitcase, and some are heavy enough to require a hand/luggage cart to move. However, this type of device is still feasible to maneuver within various areas of a transit system, including on platforms and within trains and buses. The advantage of these mobile detectors is that they allow a variety of screening locations. Randomly altering screening locations may act as a high deterrent to terrorists. Handheld Wands. Handheld wands are metal detectors used to detect weapons and contraband or trace detectors used to detect traces of explosives. Wands that are able to de- tect both metallic and nonmetallic objects concealed under clothing are under development.25 Walk-Through Portals. Walk-through portals can house traditional X-ray detectors, X-ray backscatter technol- ogy, or trace detection technologies. For trace detection technologies, the puffer method is used to direct streams of air that will dislodge explosive traces on clothing (if there are any) so that the detector will be able to identify them.26, 27 Fingertip Scan. The scan is small enough to be integrated into transit ticketing machines and could reduce potential delays that may be caused by other detection methods. Also, a detection device integrated into turnstiles is being tested by TSA. Facial Recognition. Facial recognition technology has been used for surveillance and identification of suspected ter- rorists or criminals. Facial recognition is also in use by some states for identification purposes in the issuance of driver’s li- censes and identification cards. The advantage of this tech- nology is that images can be acquired using standard camera or video equipment and can be compared against static pho- tos without user cooperation. The use of this technology in transit terminals could assist officers in identifying terrorists and criminals. The disadvantages of this technology include a need for secondary screening (because the technology cur- rently has a high false rejection rate) and privacy concerns. Baggage Screening Technology EDS Scanner. EDS is a system certified by TSA to find the “types, amounts, and configurations” of explosives than can bring down an airliner. Currently, EDS scanners all use CAT scanning technology, but not all EDS scanners will use CAT scanning in the future. A 1999 report points out that in this screening device a CAT scan uses medical technology housed in an EDS scanner to identify explosives and contraband. The equipment has the following key disadvantages: it is large (possibly too large for many locations within a transit system), extremely heavy, and expensive ($1 million or more per unit).28 Document Scan. A document scanner is a tabletop machine that evaluates tickets and other documents for traces of explosives. Portable Devices. Handheld detectors may also be used to screen baggage. Handheld Wands. Handheld detectors may also be used to screen baggage. Vehicle Screening Technology Car-Bomb Screener. One type of detection equipment that may be used to screen for vehicle-borne bombs is a mo- bile van or truck that houses explosives detection technology and sampling equipment. The van moves alongside a target vehicle and alerts the screener if a bomb is detected. This method is suitable for ferry terminals, which offer sufficient space for this type of screening technology. 17 27 GAO, Aviation Security: Progress Made in Systematic Planning to Guide Key Investment Decisions, but More Work Remains (Testimony before the Subcom- mittee on Homeland Security, Committee on Appropriations, House of Representatives—Statement of Cathleen A. Berrick, Director, Homeland Secu- rity and Justice Issues), GAO-07-448T (Washington, DC: GAO, February 2007). 28 Panel on Assessment of Technologies Deployed to Improve Aviation Security, Commission on Engineering and Technical Systems, Assessment of Technologies Deployed to Improve Aviation Security: First Report (Washington, DC: National Research Council, 1999). 24 Committee on the Review of Existing and Potential Standoff Explosives Detec- tion Techniques, Existing and Potential Standoff Explosives Detection Techniques (Washington, DC: National Research Council, 2004). 25 S. G. Haupt, S. Rowshan, and W. C. Sauntry, TCRP Report 86: Public Transporta- tion Security—Volume 6: Applicability of Portable Explosive Detection Devices in Transit Environments (Washington, DC: Transportation Research Board of the National Academies, 2004). 26 Panel on Assessment of Technologies Deployed to Improve Aviation Security, Commission on Engineering and Technical Systems, Assessment of Technologies Deployed to Improve Aviation Security: First Report (Washington, DC: National Research Council, 1999).

Technology Assessment In assessing PSI technologies, the first logical step would be to evaluate the operational feasibility of the technology types in a transit environment. The second step would be to com- pare technologies based on the following factors: accuracy, operational issues, legal issues, customer acceptance, health issues, and cost. If an objective evaluation is desired, the com- peting technologies would need to be implemented in the same location under the same conditions; otherwise, the test results may not be comparable. Once a technology has been selected, there are additional factors to consider in selecting a specific vendor and equipment model. These factors include the portability of the equipment, alarm capability, detection states, start-up time, resistance to interferants, power capa- bilities, battery needs, operational environment, and durabil- ity.29 Finally, a pilot test is recommended to ensure that the selected model does indeed function as expected. Details about these assessment criteria are provided in Appendix B. It should be noted that secondary inspections are always required to identify the source of an alarm, and the efficiency and effectiveness of secondary inspections should be consid- ered by the agency in the selection of the PSI method for secondary inspections as well. PSI Using Canines Canine teams are viewed by many transit systems as a cost- effective way to enhance security. This PSI method, which has been used by airports and some transit agencies for a num- ber of years in narcotics detection, is also perceived as mini- mizing constitutional and liability issues. In late 2005, TSA introduced a National Explosive Detection Canine Team to encourage the use of canine teams for explosives detection on transit systems. Ten transit agencies are a part of the National Explosive Detection Canine Team established by the TSA. The agencies selected for the program are the following: the MBTA, the San Francisco Bay Area Rapid Transit District (BART), the Southeastern Pennsylvania Transportation Authority (SEPTA), the Washington Metropolitan Area Tran- sit Authority (WMATA), the Port Authority Trans-Hudson Corporation (PATH), the Chicago Transit Authority (CTA), the Los Angeles County Metropolitan Transportation Au- thority (Metro), the Maryland Transit Administration (MTA), the San Francisco Municipal Railway (Muni), and the San Diego Trolley, Inc. (SDTI). Other agencies using canine teams include New York City Transit (NYCT), New Jersey Transit (NJ TRANSIT), Dallas Area Rapid Transit (DART), MTA Metro-North Railroad (Metro-North), and Tri-County Metropolitan Transportation (TriMet).30 An important advantage of the canine teams of the National Explosive Detection Canine Team program is that they are not only able to detect explosives and clear suspicious packages but they can also follow trace residues to their source. Other canine teams that are already in use at the agencies that are part of the National Explosive Detection Canine Team program have been trained to perform one or more of these security- and safety related duties: act as deterrent patrols in stations, on plat- forms, in vehicles, in transfer centers, and in parking facilities; support special events management or crowd control; track persons, including lost or missing children; perform safety checks of transit facilities; locate victims during emergencies; support narcotics searches and forfeiture programs; pursue or search for persons who threaten the canine handler or other persons; and defend and/or protect public safety officers or other persons. Disadvantages of canines include their short effective work period and the inability of the canine to inform the handler when they have become ineffective. The latter is significant because the handler may believe that the canine is continuing to perform inspections when it is not. Although its publication predated TSA’s National Explosive Detection Canine Team program, the research reported in the second volume of TCRP Report 86: Public Transportation Security (titled Volume 2: K9 Units in Public Transportation: A Guide for Decision Makers) indicated some advantages and disadvantages of using canine teams. The advantages of using canine teams were the following: • Use of canines is good for public relations, supports out- reach with community and media, and provides a strong symbol for public safety. • Canines are an effective tool for deterrence and order maintenance, passengers generally like the canine unit, and criminals are often fearful of trained police dogs. • Use of canines supports a higher level of officer safety, and criminal fear of dogs reduces resistance during apprehen- sion. • Canines provide an effective resource for facility searches. One canine team can perform the work of four patrol officers. • Canines are the most effective resource available for nonrepetitive detection of narcotics and explosives; no technology or other resource is better. • Grants are currently available for dual function patrol and drug detection dogs. 18 29 A. Fatah, J. Barrett, R. Arcilesi, K. Ewing, C. Lattin, M. Helsinki, Guide for the Selection of Chemical Agent and Toxic Industrial Material Detection Equipment for Emergency First Responders, NIJ Guide 100-00 (Washington DC: National Insti- tute of Justice, June 2000). 30 DHS, “TSA Expanding National Explosives Detection Canine Teams to Mass Transit and Commuter Rail Systems,” DHS Press Release (Washington, DC: TSA, October 6, 2005).

The disadvantages of using canine teams were the following: • Consequences of poor planning are exacerbated by the importance of initial decision making to program capabil- ities and performance. Bad decisions cannot easily be overcome. • Reliance on outside technical support is often necessary to start a canine program, a major vulnerability for a system new to this function. • High program start-up costs, not averaged evenly over time, place a large emphasis on cost savings during the phase of project when spending is most essential. • The difficulty of finding good dogs. Patrolling the trans- portation environment places additional strains on canines; selection testing is critical, but it is also expensive and not ready made for public transportation. • The difficulty of selecting the right handler. Public trans- portation systems with limited experience may value the wrong traits or fail to recognize potential shortcomings prior to a major investment. • The legal and public relations consequences of bites. The public has zero tolerance for what may be perceived as inappropriate force exerted by police dogs. • The high demands of canine administration on supervisors with other responsibilities. Scheduling challenges limit availability of canines for service. • Success requires a long-term investment—several months to a year. • Constant effort is required to ensure that law enforcement and operations personnel are using the resources of the canine unit. The estimated initial cost for one canine team that includes one handler and one canine was $118,650. This includes the handler’s salary of $60,000 and initial training expenses of $9,000.31 Canine teams may be the only short-term method of screening a large number of people arriving in a terminal for the presence of explosives, as TSA is demonstrating at the Metropolitan Atlanta Rapid Transit Authority (MARTA). The dogs, however, must be trained to focus on people rather than objects. Additional costs for canine teams are continuing quality control and testing and the cost of ensuring proper control of explosives or simulants used in testing and training, particularly to prevent cross contamination. Behavioral Assessment Two long-standing law enforcement techniques—drug courier profiling32 and hijacker profiling33—both employ the concept of behavioral assessment to detect and deter crime. As of September 2005, according to the GAO, behavior assessment is being utilized by at least eight rail transit systems as a countermeasure to terrorism.34 As of November 2006, there are several programs under which transportation authorities conduct behavioral assess- ments to screen passengers. These programs include TSA’s Screening of Passengers by Observation Techniques (SPOT) program, TSA’s Visible Intermodal Prevention and Response (VIPR) teams, and other TSA programs, as well as the Behavior Assessment Screening System (BASS) and the Behavioral Pattern Recognition program. SPOT SPOT is based on a previous TSA program called the Passenger Assessment Screening System, which was itself based on BASS. As of July 2006, SPOT was in use in 12 inter- national airports in the United States and in trial runs in several smaller airports.35 The TSA program, SPOT, employs routine screeners who have received an extra 4 days of class- room training in observation and questioning techniques and 3 days of field practice.36 TSA describes the SPOT program as using “behavior observation and analysis techniques to iden- tify potentially high-risk passengers” and further asserts that “individuals that exhibit suspicious behaviors, such as physical and physiological reactions, may be required to un- dergo additional screening.”37 TSA screeners have no law enforcement powers, so they cannot conduct interrogation themselves.38 According to one source, screeners using SPOT 19 31 J. Balog, P. Bromley, J. Strongin, A. Boyd, J. Canton, and D. Mitchell, TCRP Report 86: Public Transportation Security—Volume 2: K9 Units in Public Trans- portation: A Guide for Decision Makers (Washington, DC: Transportation Research Board, National Research Council, 2002). 32 See, e.g., United States v. Montoya de Hernandez, 473 U.S. 531 (1985). 33 United States v. Bell, 464 F.2d 667 (2d Cir. 1972). When airplane hijacking be- came a major concern in the 1970s, detection relied heavily upon hijacker profiling and traditional policing. United States v. Moreno, 475 F.2d 44, 47 (5th Circ. 1973), cert. denied, 414 U.S. 840 (1973). 34 GAO, Passenger Rail Security: Evaluating Foreign Security Practices and Risk Can Help Guide Security Efforts (Testimony Before the Committee on Transportation and Infrastructure, Subcommittee on Highways, Transit, and Pipelines, House of Representatives—Statement of JayEtta Z. Hecker, Director, Physical Infra- structure Issues), GAO-06-557T (Washington, DC: GAO, March 29, 2006), 10. www.gao.gov/new.items/d06557t.pdf. 35 J. Martin, “Behavior Assessment: Targeting Suspects Scientifically,” GSN: Government Security News. www.gsnmagazine.com/jul_06/behavior.html. 36 E. Lipton, “Faces, Too, Are Searched at U.S. Airports,” New York Times, August 17, 2006, Late Edition—Final, sec. A, p. 1, col. 3. www.nytimes.com/2006/ 08/17/washington/17screeners.html. (Article available for purchase at this URL.) 37 TSA, “Where We Stand: TSA Trains Hard for New Threats.” www.tsa.gov/ press/where_we_stand/training.shtm. 38 E. Lipton, “Faces, Too, Are Searched at U.S. Airports,” New York Times, August 17, 2006, Late Edition—Final, sec. A, p. 1, col. 3. www.nytimes.com/2006 08/17/ washington/17screeners.html. (Article available for purchase at this URL.)

look for “anxious, frightened, or deceptive behaviors.” They then question passengers exhibiting such behaviors and score their answers against the SPOT index. The screeners then have four choices: they can (1) send the passenger through more intense checkpoints; (2) call local or airport police, who can conduct further questioning; (3) call in counterterrorism experts; or (4) take no further action.39 The Israeli security official who helped train the officers for the BASS program has recommended that secondary questioning also be done by an officer with behavioral training.40 VIPR Teams In an attempt to reach beyond air security, the TSA formed teams planned to patrol, among other things, mass transit systems in Atlanta, Philadelphia, Baltimore, and Washington, D.C., during December 2005. The teams included “two air marshals, one TSA bomb-sniffing canine team, one or two transportation security inspectors, one local law enforcement officer, and one other TSA employee.”41 However, it appeared that the program was not coordinated with local transit authorities, and it was significantly scaled back.42 The pro- gram was deployed in September 2006 at MBTA stations that are significant links to Logan International Airport.43 Other TSA Programs During the 2005 presidential inauguration, WMATA police were trained to observe passengers for suspicious behavior, including “avoid[ing] eye contact, loiter[ing], or appear[ing] to be looking around transit stations more than other passen- gers” and to question persons exhibiting such behavior about their activities and planned destinations. Security experts commenting on these procedures suggested that police should be able to articulate a reason for questioning a passenger.44 BASS Since September 11, 2001, state troopers at Boston’s Logan Airport trained in BASS have observed passengers for suspi- cious behavior and questioned passengers whose behavior triggers the system. Questioning may seem routine, such as asking the passenger’s destination and requesting identifica- tion. The officers look for stress indicators in the passenger’s response that suggest the person may be prepared to under- take a suicide mission.45 BASS purports not to use “apparent race, ethnicity or religion as a basis of suspicion.”46 However, as discussed below, a lawsuit has been filed alleging that the program at Logan Airport employs illegal racial profiling. Dallas/Fort Worth International Airport has also deployed BASS-trained officers.47 Transit authorities have begun to employ BASS training. WMATA has provided an 8-hour BASS training course to transit police.48 The course teaches officers to “assign a number value to certain behaviors and the total number determines the type of response required.”49 According to the Metro Transit police, posing operational questions to transit personnel, carrying maps or blueprints, or taking pictures of infrastructure would be deemed suspicious activities. The course also includes interview techniques, risk mitigation measures, and explanation of Fourth Amendment issues.50 When the MBTA resumed random bag inspections in October 2006, it announced that it would also deploy tactically uniformed teams trained in antiterrorism and behavioral recognition techniques.51 20 39 Associated Press, “MSP to Test Behavioral Screening System” (Minneapolis, MN: WCCO-TV, December 4, 2005). http://wcco.com/local/local_story_ 338134911.html. 40 E. Lipton, “Faces, Too, Are Searched at U.S. Airports,” New York Times, August 17, 2006, Late Edition—Final, sec. A, p. 1, col. 3. www.nytimes.com/ 2006/08/17/washington/17screeners.html. (Article available for purchase at this URL.) 41 S. K. Goo, “Marshals to Patrol Land, Sea Transport: TSA Test Includes Surveillance Teams on Metro System,” Washington Post, p. A1, Decem- ber 14, 2005. www.washingtonpost.com/wp-dyn/content/article/2005/12/13/ AR2005121301709.html. 42 S. K. Goo, “New TSA Surveillance Tactic Curtailed Officials Confused over Test of Air Marshals at Transit Hubs: Metro Not in Program,” Washington Post, p. A2, December 15, 2005. www.washingtonpost.com/wp-dyn/content/article/ 2005/12/14/AR2005121402366.html. CBS and Associated Press, “TSA Expands Marshal’s Scope: Officers Descending on Transit Systems, Bus Stations, Ferries” (CBS News website, December 14, 2005). www.cbsnews.com/stories/2005/12/ 14/terror/main1124534.shtml. 43 M. Daniel, “Heightened Security at Bus, Train Stops: Teams Assigned at Busiest Hubs to Logan Airport,” Boston Globe, September 14, 2006. http://www. boston.com/news/local/articles/2006/09/14/heightened_security_at_bus_train_ stops. 44 S. K. Goo, “Metro Officers Keep a Keen Eye on Riders: New Behavioral Profiling Techniques, TSA Training Help Target Suspicious Subway Passengers,” January 10, 2005, p. A6. www.washingtonpost.com/wp-dyn/articles/A61700-2005Jan9. html. 45 A. Beshkin, “U.S. Airport Screeners Look for Behaviors” (NewsVOAcom [Voice of America website], October 2, 2006). www.voanews.com/english/ archive/2006-10/2006-10-02-voa40.cfm. 46 Institute of Police Technology and Management, “Terrorist Identification and Interdiction” (Brochure for 2-day course offered in June 2005). www.Iptm. Org/Flyers/027152.Pdf. 47 M. Grabell, “Dallas/Forth Worth Airport Police Train to Detect Terrorists: Behavior Screening Helps Airport Officers See Suspicious Situations,” Dallas Morning News, October 3, 2004. Article accessed and available at PoliceOne.com (title: “Texas Police Train to Detect Terrorists at Airport”). www.policeone.com/ training/articles/92506/. 48 WMATA, “Metro Security Enhanced Since the 2005 London Transit Bomb- ings” (WMATA press release, July 6, 2006). http://www.wmata.com/about/ met_news/PressReleaseDetail.cfm?ReleaseID=1296. 49 WMATA, “Metro Transit Police to Take Course to Identify Terrorists” (WMATA press release, March 9, 2006). www.wmata.com/about/met_news/ PressReleaseDetail.cfm?ReleaseID=1140. 50 Ibid. 51 M. Daniel, “MBTA Transit Police to Resume Random Bag Inspections” (MBTA Press Release, October 11, 2006). http://transitpolice.us/Press-News%20 Releases%202006.htm.

Behavioral Pattern Recognition Raffi Ron, an Israeli security expert, has trained personnel who work throughout airports, including parking lot attendants and flight attendants, in recognizing suspicious behavior. These personnel receive 4 hours of training about what behaviors to look for and where to report any suspi- cions. Law enforcement personnel receive 5 days of training that covers techniques for interviewing persons suspected of posing a terrorist threat, tactical response, and suspicious object handling. After the classroom instruction, the officers receive 4 hours of on-the-job training from experienced personnel.52 The National Transit Institute (NTI) has developed a Terrorist Activity Recognition and Reaction (TARR) course for transit employees who have direct contact with the public. According to the course description on the NTI website: The goals of the course are to provide participants with the knowledge and skills to: • Explain the importance of identifying and reporting pre- attack terrorist activity • Recognize the difference between normal, suspicious, and dangerous activity • Define their role in recognizing and reacting to suspicious activity • Describe their immediate actions when confronted with dangerous activity. Tuition is waived for federal, state and local government employees who work in transportation or related areas. (See http://www.ntionline.com/CourseInfo.asp?Course Number=SA006a.) Legal Implications of PSIs The decision-making process concerning the implementa- tion of passenger screening involves numerous considerations. A transit agency must consider whether to implement passenger screening at all, and if so, under what conditions. Should screening be suspicionless or based on behavioral profiling?53 Should screening be conducted daily or based on threat levels? What method should be used for conducting the screening? These issues are interrelated, as screening methods that might be inappropriate for daily use may be appropriate under more specific circumstances. Each of the decisions concerning passenger screening has legal as well as operational implications. The legal implications will inform both the development and implementation of the policy, including the need for training to help minimize liability. Passenger security screening can be accomplished using visual inspections (including behavioral assessments), physical inspections, explosives detection canines, X-ray equipment, and other explosives detection technology. These methods may vary not only in effectiveness, intrusiveness, cost, and efficiency, but also in their legal ramifications with regard to constitutional and tort law. In fact, some methods that are less vulnerable to attack on constitutional grounds may be more vulnerable to tort actions. However, the basic principles of sound planning needed to develop a constitu- tional passenger security screening program should also result in a program reasonably defensible against tort actions. The legal issues examined in this research are the following: • Constitutional limitations on conducting PSIs (fixed checkpoints, behavioral assessment, consent, profiling, drug-seeking or explosives detection dogs, luggage searches, administrative searches, specials needs, airport security searches, and transit searches). • Tort liability (in general, for constitutional violations, for invasion of privacy, for failure to exercise sufficient care, and for exposure to canines). • Screening technology issues (tort liability for invasion of privacy, tort liability for false/true innocuous positives, and state health restrictions on certain screening technologies). • Legal implications of providing accommodations to people with disabilities. These issues are discussed at length in the Appendix D of this report. Conceptually, random transit security screening procedures can be shown to meet the constitutional requirements that they are (1) used in circumstances in which requiring reasonable suspicion or a warrant is impractical and (2) used to fulfill a substantial government need.54 Procedures will be judged based on their intrusiveness (which will be balanced against the governmental need), will have to be subject to neutral criteria,55 and must be reasonably effective. Notice of random inspec- tions reduces the intrusiveness of the search. Prospective pas- sengers should be afforded the opportunity to exit the system 21 52 R. Elliott, “Assessing Threats from Passengers,” Security Management, September 2006. 53 MBTA has used a behavioral screening system to identify passengers exhibit- ing suspicious behavior. See GAO, Passenger Rail Security: Enhanced Federal Leadership Needed to Prioritize and Guide Security Efforts (Report to Congres- sional Requesters), GAO-05-851 (Washington, DC: GAO, September 2005), 53. For discussion of the importance of training in recognizing terrorist behavior see “Statement by Raffi Ron to the Senate Committee on Homeland Security and Governmental Affairs, September 21, 2005.” http://hsgac.senate.gov/_files/ 092105Ron.pdf. 54 See United States v. Martinez-Fuerte, 428 U.S. 543 (1976). Inspections based on behavioral assessments will rely on reasonable suspicion rather than random selection. 55 See Michigan Dept. of State Police v. Sitz, 496 U.S. 444 (1990).

without being subject to random inspection, and doing so should not, in and of itself, be considered suspicious behavior. The procedures will have to be clearly aimed at something (e.g., preventing explosives from entering the transit system) other than general law enforcement,56 and should protect a need that cannot be protected by general policing. Not all security threats may be sufficient to establish a vital government interest as a matter of law. Deterrence may be judged a sufficient goal, and an inspection protocol that generates sufficient uncertainty for would-be terrorists may be judged reasonably effective under the legal balancing-of-interests test, even though many pas- sengers are not searched. It should be noted that the inspection protocol should not vitiate the normal principles of reasonable suspicion, and training should cover differences between legitimate refusal to be inspected and behavior that can be reasonably considered suspicious. Legal Implications of Behavioral Assessments Introduction The legal issues likely to be posed by conducting behav- ioral assessment to screen transit passengers include the reasonableness of any resulting searches and seizures57 under both federal and state constitutions, and challenges to such searches and seizures as being race-based procedures in violation of the Fourteenth Amendment58 and relevant state constitutions. In the heyday of airline hijacker profiling, some concern was expressed about pretexting, that is, using the hijacker profiles as an excuse to stop suspected drug offenders.59 The use of behavioral assessment in the context of transit counterterrorism, let alone the law governing such use, is not yet sufficiently developed to determine whether pretexting will become an issue. Some states have rules concerning racial profiling that are stricter than the federal government’s. Therefore, to the extent that racial/ethnic profiling is employed, caution is warranted because behav- ioral assessment is an area in which state and federal law may differ substantially.60 Recent Cases There do not appear to be any recent decisions involving be- havioral assessment in transportation, let alone in the transit context. The airport-related case of Downing v. Massport 61— as of November 2006 still in pre-trial status—appears to be the only action challenging the constitutionality of a current behavioral assessment program. The following information about the case is provided for illustrative purposes only. There is no legal analysis inferred or implied. Downing v. Massport involves a challenge to BASS imple- mentation at Logan International Airport. The plaintiff alleges that he was unlawfully detained at the airport by state troopers and threatened with arrest unless he produced iden- tification and his travel documents. The plaintiff’s central argument is that state troopers took these actions despite the fact that there was no reasonable suspicion that he was engaged in wrongdoing. The central allegations of Downing v. Massport are that the BASS training does the following: • Directs or authorizes state police troopers to stop, question, and/or arrest certain individuals at Logan despite the absence of reasonable suspicion that the individuals were committing, had committed, or were about to commit any crime; • Authorizes state police officers to deny access to Logan to any person who refuses to cooperate with police requests for identification or other information; and • Effectively condones and encourages racial and ethnic profiling.62 The plaintiff is an African American and the national coordinator of the American Civil Liberties Union’s (ACLU’s) Campaign against Racial Profiling. The following summarizes the description given in the complaint of his encounter with state troopers at Logan: 22 56 See City of Indianapolis v. Edmond, 531 U.S. 32 (2000). Plaintiffs in MacWade v. Kelly, 2005 WL 3338573 (S.D.N.Y.) argued unsuccessfully that a bag search policy on the New York City subway was ordinary law enforcement. 57 For a more detailed discussion of search and seizure cases, see J. Waite, TCRP Legal Research Digest 22: The Case for Searches on Public Transportation (Washington, DC: Transportation Research Board of the National Academies, 2005). 58 The Supreme Court, which has upheld some ethnic profiling, United States v. Brignoni-Ponce, 422 U.S. 873, 878 (1975); United States v. Martinez-Fuerte, 428 U.S. 543, 563 (1976), has held that it will decide challenges to searches motivated by race under the Fourteenth, rather than the Fourth, Amendment. Any such searches will be subject to strict scrutiny. Whren v. United States, 517 U.S. 806 (1996). 59 Some judges expressed concern that airport searches based on hijacking profiles were turning up far more illegal drugs than the weapons that were ostensibly the targets of the searches. See United States v. Legato, 480 F.2d 408, 414 (5thCir. 1973) (Goldberg, J., specially concurring), cert. denied, 414 U.S. 979 (1973); United States v. Cyzewski, 484 F.2d 509, 515-16 (5th Cir. 1973) (Thornberry, J., dissenting), cert. denied, 415 U.S. 902 (1974). However, one commentator has suggested that since air hijacking and drug courier profiling have come into use, the only objections have been in law review articles and dissenting opinions. J. L. Miller, Search and Seizure of Air Passengers and Pilots: The Fourth Amendment Takes Flight, 22 TRANSP. L.J. 199, 209–11 (1994). 60 See “Profiling” in TCRP Legal Research Digest 22, pp. 18–20. 61 King Downing, Plaintiff, v. Massachusetts Port Authority; the Massachusetts Department of State Police, State Police Trooper Thompson, State Police Sergeant Croxton, Thomas G. Robbins, and Peter J. Didomenica, Defendants. Complaint and Demand for Jury Trial, November 10, 2004. www.aclu.org/FilesPDFs/ downing.pdf. 62 Ibid., 4.

After plaintiff, who was sporting a short beard and wearing casual clothing, deplaned at Logan, he made a phone call in a general access area of the airport. The plaintiff noticed that a state trooper was standing near him, apparently trying to overhear his conver- sation. The trooper demanded that plaintiff produce identifica- tion. The trooper refused to say why he wanted to see the identification, but told plaintiff that he would be removed from the airport if he refused to provide identification. Plaintiff then left the airport, but the trooper followed him outside and again demanded to see identification, responding to plaintiff’s question whether he was under arrest, but refusing to state the grounds for the arrest. Before detaining plaintiff, the trooper did not ask any questions about plaintiff’s travel that might have dispelled any suspicions he might have had about plaintiff’s presence at Logan. The trooper radioed for assistance. A superior officer told plain- tiff that he was being detained because the first trooper had concluded that he had acted suspiciously, but the superior officer could not, or would not, provide any description of the allegedly suspicious behavior or what had aroused the trooper’s suspicion. Under threat of being handcuffed and taken to police lock-up, plaintiff produced his driver’s license. After running the license through the police computer, the troopers insisted that plaintiff, under threat of being placed on Logan’s trespass list, produce his airline ticket. After doing so plaintiff was released.63 Plaintiff has alleged that the BASS training employs a lesser standard than reasonable suspicion, uses race and ethnicity as a factor in determining whether a person is “suspicious,” and uses a person’s assertion of his constitutional rights as a basis for fur- ther detention or interrogation.64 Plaintiff further alleged that his treatment violated Articles 1 and 14 of the Massachusetts Declaration of Rights, the Fourth and Fourteenth Amendments to the United States Constitution, and 42 U.S.C. § 1983. Although discretion is not addressed in the complaint, the ACLU has elsewhere asserted that BASS appears to leave the determination of what constitutes unusual or anxious behavior requiring action to the discretion of individual officers.65 Analysis of Legal Issues Based on existing case law and as illustrated by the Downing complaint, the aspects of behavioral assessment that may raise constitutional issues include the following: • Basis for reasonable suspicion – Use of subjective versus objective criteria – Amount of discretion exercised by officials conducting the assessments – Amount of training afforded the officials conducting the assessments • Use of racial/ethnic criteria • Consent • Request for identification • Questioning passengers about destination, travel plans, and related information. Basis for Reasonable Suspicion.66 The validity of hijacker profiles was generally recognized as a basis for reasonable suspicion without much analysis.67 In one case, a defendant was searched for meeting a hijacker profile because he “paid cash for his tickets, did not furnish a phone number on his pas- senger information sheet, was Hispanic, was scheduled to board a flight within the range of Cuba, bought two one-way tickets, and declined to check any of the couple’s five pieces of luggage.”68 Case review shows that the hijacker profile appears to have been generally used to move suspects to secondary screening and does not appear to have been enough in and of itself to have justified a search.69 The officer’s experience in using a profile appears to be a factor in upholding its legitimacy in developing a reasonable suspicion to search someone.70 In addition to illustrating the importance of the officer’s experi- ence in developing reasonable suspicion, United States v. Moreno illustrated the types of factors that taken together can support reasonable suspicion. In this case, the Fifth Circuit found several facts that, taken together, constituted reasonable suspicion and justified investigating the defendant’s behavior. These facts included the following: (1) the defendant appeared 23 63 Ibid., 5–7. 64 Ibid., 7. 65 ACLU/ACLU Foundation of Massachusetts, Racial Justice Report (ACLU, June 2005), p. 3. www.aclu-mass.org/pdf/RacialJustice.pdf. “ACLU of Massachusetts Challenges Use of Behavioral Profiling at Logan Airport” (ACLU press release, November 10, 2004). www.aclu.org/safefree/general/18765prs20041110.html. 66 The term “reasonable suspicion” came to prominence in Terry v. Ohio, 392 U.S. 1 (1968), in which the Supreme Court held that a police officer could stop and search a suspect for weapons to ensure the safety of the officer and nearby civilians, and that the basis need not rise to the level of probable cause, but could rest on “the specific reasonable inferences which [the officer] is entitled to draw from the facts in light of his experience.” Id. at 27. The Supreme Court subsequently acknowl- edged that “[a]rticulating precisely what ‘reasonable suspicion’ and ‘probable cause’ mean is not possible. They are commonsense, nontechnical conceptions that deal with the factual and practical considerations of everyday life on which rea- sonable and prudent men, not legal technicians, act.” Ornelas v. United States, 517 U.S. 690 (1996) (Internal quotes and citations omitted). Nonetheless, the Court went on to explain that reasonable suspicion is “simply . . . a particularized and objective basis for suspecting the person stopped of criminal activity.” (Internal quotes and citations omitted). Id. The Court then went on to state that “[t]he principal components of a determination of reasonable suspicion or probable cause will be the events which occurred leading up to the stop or search, and then the decision whether these historical facts, viewed from the standpoint of an objectively reasonable police officer, amount to reasonable suspicion or to probable cause.” Id. 67 E.g., United States v. Skipwith, 482 F.2d 1272, 1274–75 (5th Cir. 1973). See also United States v. Lopez-Pages, 767 F.2d 776, 778 (11th Cir. 1985) (upholding Eastern Airlines’ use of behavioral profile for searching passengers). 68 United States v. Lopez-Pages, 767 F.2d 776, 778 (11th Cir. 1985). 69 E.g., United States v. Bell, 464 F.2d 667, 672 (2d Cir. 1972) (The fact that the passenger met FAA’s profile of potential hijacker was found to be a legitimate factor in developing a reasonable suspicion that there was cause to stop and frisk passenger), cert. denied, 409 U.S. 991; United States v. Lopez, 328 F. Supp. 1077 (EDNY 1971) (upheld Terry-type frisk of individual at airport boarding gate on grounds of matching hijacker profile and activating magnetometer). 70 See United States v. Moreno, 475 F.2d 44, 50 (5th Cir. 1973).

to be nervous, as observed by an experienced anti-piracy officer; (2) the defendant had flown into San Antonio, taken a taxi to a downtown bus station, and returned to the airport 2 hours later; (3) the defendant had changed waiting lines and then purchased a ticket from a different airline; and (4) the defendant had a prominent bulge in his overcoat. Upon inves- tigation, the officer determined that the suspect lied to him about his whereabouts while visiting San Antonio, which further supported the finding of reasonable suspicion.71 In the context of drug-courier profiles, the Supreme Court has held that the fact that the articulated facts supporting an officer’s reasonable suspicion are consistent with the descrip- tion in a drug courier profile does not detract from their evidentiary value.72 The Supreme Court has also upheld a de- tention based on the reasonable suspicion that the defendant met the profile of an alimentary canal balloon smuggler.73 In the context of illegal immigration, the Supreme Court has upheld racial profiling to help develop reasonable suspi- cion by United States Border Patrol agents making stops along the United States–Mexico border.74 The fact that the agents were policing the border was integral to the Court’s determination.75 While Mexican ancestry was deemed a rele- vant factor in developing reasonable suspicion of illegal immigration, it was not deemed sufficient as the sole factor.76 The officers’ experience in enforcing immigration laws was arguably a factor in the Court’s finding on this point.77 The Court subsequently approved the use of ethnic classifications as one factor in deciding which cars to refer to a secondary fixed checkpoint, stating “even if it be assumed that such referrals are made largely on the basis of apparent Mexican ancestry, we perceive no constitutional violation.”78 Use of Racial/Ethnic Criteria. The Supreme Court has held that it will decide challenges to searches motivated by race under the Fourteenth, rather than the Fourth Amendment. Any such searches will be subject to strict scrutiny.79 Lower courts have come to different decisions depending on whether racial identity is the sole factor in developing reasonable suspicion or one of several factors.80 In some states, any pro- gram that is challenged for employing racial profiling will also be subject to challenge as violating state law, as a number of states have either outlawed racial profiling by statute or have invalidated pretextual stops involving racial profiling.81 Consent.82 One possible rationale for questioning and inspecting passengers is consent. The Supreme Court has held that the voluntariness of consent to search is a question of fact to be determined from “the totality of all the circumstances,” and that knowledge of the right to refuse consent is merely one factor to consider.83 Therefore, although the government does have the burden of establishing that consent to a search was vol- untary, it need not, in order to meet that burden, establish that the person searched knew that he had the right to refuse the search.84 In order to give valid consent, however, the situation must be such that a reasonable person would feel free to leave.85 Some states have increased the burden of proof of establishing consent beyond that required by the Supreme Court. New Jer- sey, for example, has held that the subject of a search must know of the right to refuse in order for consent to be voluntary.86 Request for Identification. Police are free to ask any passenger for identification.87 The critical issue is the point at which the passenger can no longer refuse to provide the iden- tification. The Supreme Court has long held that a “stop and identify” statute is unconstitutional when the initial stop is not based on “specific, objective facts establishing reasonable suspicion to believe the suspect was involved in criminal activity.”88 In addition, “stop and identify” statutes that do not provide a clear standard for determining what a suspect must do to comply are unconstitutional.89 The Court has held, however, that a statute requiring the subject of a valid Terry stop to provide his or her name is constitutional. Of potential significance in the context of requiring identifica- tion as part of behavioral assessment, the Court noted that the Nevada statute at issue in Hiibel “does not require a suspect to give the officer a driver’s license or any other docu- 24 71 United States v. Moreno, 475 F.2d 44 (5th Cir. 1973), cert. denied, 414 U.S. 840 (1973). 72 United States v. Sokolow, 490 U.S. 1, 7 (1989). Justice Brennan, dissenting, argued that “[r]eflexive reliance on a profile of drug courier characteristics runs a far greater risk than does ordinary, case-by-case police work of subjecting in- nocent individuals to unwarranted police harassment and detention.” Id. at 13. 73 United States v. Montoya de Hernandez, 473 U.S. 531 (1985). 74 United States v. Brignoni-Ponce, 422 U.S. 873 (1975). 75 S. M. Haines, “Comment: Rounding Up the Usual Suspects: The Rights of Arab Detainees in a Post-September 11 World,” Arkansas Law Review 57, no. 146, (2004): 122. 76 United States v. Brignoni-Ponce, 422 U.S. 873, 885–86 (1975). 77 Haines, “Comment: Rounding Up the Usual Suspects,” 123. 78 United States v. Martinez-Fuerte, 428 U.S. 543, 563 (1976) (footnote omitted). Justice Brennan, dissenting, stated: “Today we are told that secondary referrals may be based on criteria that would not sustain a roving-patrol stop, and specif- ically that such referrals may be based largely on Mexican ancestry.... That law in this country should tolerate use of one’s ancestry as probative of possible crimi- nal conduct is repugnant under any circumstances.” 428 U.S. 571, n.1. 79 Whren v. United States, 517 U.S. 806 (1996). 80 Cf. United States v. Weaver, 966 F.2d 391 (8th Cir. 1992) (officer had grounds for reasonable suspicion, only one of which was racial identity: no Fourth Amendment violation) and Gonzalez-Rivera v. INS, 22 F.3d 1441, 1448 (9th Cir. 1994) (racial identity was sole factor, unconstitutional). 81 See Waite, TCRP Legal Research Digest 22, 18–20. 82 For a more detailed discussion of consent cases, see Waite, TCRP Legal Research Digest 22, 16–18. 83 Schneckloth v. Bustamonte, 412 U.S. 218, 227 (1973). 84 412 U.S. 248–49. 85 Florida v. Royer, 460 U.S. 491, 502 (1983). 86 State v. Johnson, 346 A.2d 66, 68 (N.J. 1975). 87 See INS v. Delgado, 466 U.S. 210, 216 (1984). 88 Hiibel v. Sixth Judicial District Court of Nevada, Humboldt County, 124 S. Ct. 2451, 2457 (2004), citing Brown v. Texas, 443 U.S. 47, 52 (1979). 89 Hiibel v. Sixth Judicial District Court of Nevada, Humboldt County, 124 S. Ct. 2451, 2457 (2004), citing Kolender v. Lawson, 461 U.S. 352 (1983).

ment.”90 The Court noted that police discretion to arrest is limited in that in order to arrest the request for identification must be “reasonably related to the circumstances justifying the stop.”91 Individual state constitutions may place greater restrictions on the right of police to request identification than does the Fourth Amendment. Questioning about Destination, Travel Plans, and Related Information. The Fourth Amendment is not relevant if an official merely approaches an individual on the street or in another public place and asks if he or she is willing to answer some questions.92 When, however, there is some constraint on the individual’s liberty, Fourth Amendment requirements come into play.93 Thus, in order to detain a person to question him or her, or because he or she has refused to be questioned, the police should have a reasonable suspicion that the person is involved in criminal activity. A refusal to answer questions should not be the sole basis of reasonable suspicion. Individual state constitutions may place greater restrictions on the right of police to question passengers than does the Fourth Amendment. In summary, factors that may enter into evaluating the reasonableness of the officer’s suspicion include whether the criteria are subjective or objective, the amount of discretion exercised by the officers conducting the assessments, and the amount of training/experience of the officers conducting the assessments. The specific issues posed by particular behavioral assess- ment programs will depend in part on aspects of the protocol such as the following: • The purpose of the behavioral assessment (e.g., deterrence, detection, or back-up for other inspectors); • Whether the behavioral assessment includes objective indicators, such as interest in operational details, or relies solely on subjective indicators, such as appearing nervous; • The amount of discretion afforded the inspecting officer; • Whether a person who declines to provide information will be detained, will be asked to leave the system, or will have no further action taken; • Whether the protocol includes questions designed to con- firm or dispel suspicion before further actions are taken; • Whether the behavioral assessment will be used to move passengers who reach a certain threshold to secondary screening; and • The location in the system where the behavioral assess- ment is conducted—on arriving passengers, departing passengers, or both. The effect of each aspect of the protocol listed above on the risk that a court may find the protocol invalid is as follows: • Purpose. The reasonableness of the protocol will be affected by the relation between the articulated purpose and elements of deployment such as location of assess- ments and treatment of questioned passengers. For exam- ple, if the purpose is deterrence, the existence, but not the operational details, of the program should be made public. • Indicators. The more subjective the indicators, the more vulnerable the protocol is to challenges of unreasonable vagueness, abuse of discretion by the inspecting officer, and racial profiling. Having multiple indicators may mitigate legal risk. Use of racial/ethnic characteristics as an indicator may be illegal in some states. Even where racial/ethnic pro- filing is not per se illegal, using such characteristics as the sole indicator may increase the risk that a court will find the protocol unconstitutional. • Discretion. Unlike random inspections, behavioral assess- ments require a modicum of discretion on the part of the inspecting officer. Nonetheless, the greater the inspecting officer’s discretion, the more vulnerable the protocol is to challenges of unreasonable vagueness, abuse of discretion by the inspecting officer, and racial profiling. Adequate training is key to mitigating the risk of legal challenges based on exercise of discretion. • Action taken. Actions taken based on behavioral assess- ment should have a reasonable relation to the purpose of the assessments. If, for example, the purpose is deterrence, following passengers out of the station may be inconsistent with that purpose. • Confirming/dispelling questions. Requiring the officer to ask questions to confirm or dispel reasonable suspicion should lessen the risk that a court will find the protocol unconstitutional. • Secondary screening. Employing secondary screening, par- ticularly objectively based methods such a trace/bulk detection equipment, should lessen the risk of legal challenge. • Location. The location of behavioral assessments in the transit system should be reasonably related to the purpose of conducting the assessments. The location of assessments may affect how courts view the reasonableness of the procedures in cases involving either arriving or departing passengers. 25 90 Hiibel v. Sixth Judicial District Court of Nevada, Humboldt County, 124 S. Ct. 2451, 2457 (2004). 91 Hiibel v. Sixth Judicial District Court of Nevada, Humboldt County, 124 S. Ct. 2451, 2459 (2004). Justices Breyer, Souter, and Ginsburg dissented, arguing that the police are free to question a Terry detainee to try to dispel suspicions, but that the detainee cannot be obliged to respond. Id. at 2465. 92 Fla. v. Royer, 460 U.S. 491, 497 (1983). See also Fla. v. Bostick, 501 U.S. 429 (1991). 93 United States v. Mendenhall, 446 U.S. 544, 554 (1980). Some courts have required that (1) there be a show of authority by police such that a reasonable per- son in the surrounding circumstances would not believe he was free to leave and (2) that the person yield or acquiesce to that show of authority. E.g. Cal. v. Hodari D., 499 U.S. 621, 624–29 (1991); United States v. Santamaria-Hernandez, 968 F.2d 980, 983 (9th Cir. 1992).