	Introduction

Border and Transportation Security (BTS) is a pivotal function in protecting the American people from terrorists and their instruments of destruction. The issue for Congress is how to achieve desired levels of security, while not compromising other important values in the process. In a series of three reports, a strategic approach to BTS using a variety of frameworks to clarify objectives and help identify policy options is discussed. This final report builds on the analysis presented in the first two reports, and explores possible new directions and policy options that spring directly from the analytical frameworks contained in those reports. Before doing so, however, it is useful to place this set of activities in the broader context of overall Homeland Security efforts and to review the development of congressional concern and policy approaches up to this point. The Role of Border and Transportation Security in Homeland Security

The homeland security effort can be seen as a series of concentric circles or screens, with the outer screen being that of preventive efforts launched outside the country. The continuum of activities to provide homeland security then moves through progressively smaller circles starting from more distant efforts to closer and more localized measures. The congressional response began with inquiries as to the nature of the terrorist threat and the commissioning of several studies, and was followed by specific, targeted measures to protect the nation following the events of 9/11. Interest in broader, more comprehensive substantive approaches . The Complexity of the Border Security Challenge and Selected Policy Tools Now in Use

The task of providing border and transportation security is complex both because of its scale and possible conflicts with other important national goals. (See CRS Report RL32839, Border Security: The Complexity of the Challenge , by [author name scrubbed].) The current programs designed to accomplish this interception are discussed more fully in the second report in this series: CRS Report RL32840, Border and Transportation Security: Selected Programs and Policies , by Lisa M. Seghetti, [author name scrubbed], and [author name scrubbed]. The realization that multiple points of vulnerability might be turned into expanded opportunities for interdiction has given rise to the notion of a "layered" approach to security. The basic idea of layering is that multiple and overlapping measures applied at key points in the border security environment could succeed where only more targeted measures might fail because of their rising expense, increasing conflict with other goals, or inability to cover all conceivable risks arising from opportunistic terrorist tactics. Possible New Directions and Policy Options

To pursue a layered approach to border and transportation security would mean applying some measures of security effort to each of the following points of vulnerability/opportunity:
Staff authentication —focusing on any staff involved with the transportation of people or shipment of goods; Passengers —screening anyone traveling on any of the conveyances of concern; Conveyances (passenger or cargo)—monitoring the vessel, car, truck, plane, train used in conveying travelers or goods—including concern for the physical security of the conveyance itself; Access control —implementing a system to achieve and maintain control of the physical space where the conveyances or cargo are either stored, staged, maintained, repaired, loaded, or inspected.
There is consensus that Border and Transportation Security (BTS) is a pivotal function in protecting the American people from terrorists and their instruments of destruction. The issue for Congress is how to achieve desired levels of security, while not compromising other important values in the process. This report addresses possible new approaches and policy options that might be explored by Congress to attain these goals. It is one of three CRS reports in a series that make use of analytical frameworks to better understand complex problems in BTS and to facilitate consideration of alternative policies and practices. (The first report in the series, CRS Report RL32839, Border Security: The Complexity of the Challenge, by [author name scrubbed], analyzes the reasons why BTS is so difficult to achieve. The second report CRS Report RL32840, Border and Transportation Security: Selected Programs and Policies, by Lisa M. Seghetti, [author name scrubbed], and [author name scrubbed], discusses programs now in place. This report is the last in the series).
BTS plays an important role in the broader function of providing homeland security. The overall homeland security effort can be seen as a series of concentric circles or screens, with the outer screen being that of preventive efforts launched outside the country—before terrorists or their weapons can reach the country. The next screen is interdiction efforts at the border and in the transportation system. The continuum of activities then moves through progressively smaller circles ending with emergency preparedness and response. Congressional concern over homeland security began with broad-gauged efforts to learn more about the nature of the terrorist threat, and then moved to much more specific actions following the events of 9/11. Congressional interest in broader, more strategic approaches continues—which makes this review of possible new directions and policy options timely.
Both the complexity of the challenges at the border, and the realization that multiple points of vulnerability might be turned into expanded opportunities for interdiction, have given rise to the notion of a "layered" approach to security. The basic idea of layering is that multiple and overlapping measures applied at several points in the border security environment could be more successful than more targeted measures alone. The problem in hardening a few selected targets is the rising expense of unit costs, increasing conflict with other goals, and/or inability to cover all conceivable risks posed by the shifting and opportunistic nature of terrorist tactics.
To pursue a layered approach to border and transportation security would mean applying some measure of security effort to each of the following points of vulnerability/opportunity: transportation staff, passengers, conveyances, access control, cargo and baggage, ports, and security en route. Several possible policy options are presented that flow directly from the framework presented in the three-part series of CRS reports. Before action is contemplated in any of these areas, however, it would be important to assess the priority of each step, its relative cost-effectiveness, and the level of intrusiveness and possible conflicts with other important social goals (e.g., privacy and civil liberties). This report will not be updated.