Evidence Rating for Outcomes
Crime & Delinquency | Terrorism and mass violence offenses |
Date:
Counterterrorism includes strategies, policies, practices, interventions, or tactics that are designed to prevent or respond to terrorism. Target hardening at airports is an example of a defensive counterterrorism intervention that is designed to increase the detection of potential terrorism by placing metal detectors in airports and increasing security screening of passengers before they board planes. This practice is rated Promising for significantly reducing events of airplane hijackings.
Practice Goals/Practice Components
Counterterrorism includes strategies, policies, practices, interventions, or tactics that are designed to prevent or respond to acts of terrorism. There are a number of definitions of terrorism that attempt to differentiate terrorism from other violent crimes or acts of violence. Unfortunately, there is no universal, agreed-upon definition. Terrorism, as defined by the Federal Bureau of Investigation (FBI), is the “unlawful use of force or violence against persons or property to intimidate or coerce a government, the civilian population, or any segment thereof, in furtherance of political or social objectives” (NIJ 2011). The FBI definition focuses on methods of terrorism, rather than motivation of the terrorist, and differentiates between international terrorism and domestic terrorism. Regardless of the specific definition, violence is an important component of terrorism, and can take on many forms such as kidnappings, bombings, or hijackings of planes (Sandler 2011).
Counterterrorism can take on many forms, such as defensive and proactive measures; prevention, detection, and management strategies; and law enforcement responses. Specific examples of counterterrorism strategies, tactics, and tools include (but are not limited to) buildings security, CCTV, distribution of no-fly lists, weapons detection devices, diplomatic efforts, educational programs, emergency preparedness, foreign aid, fortification of embassies, gas mask distribution, hostage negotiation, legislation, military interventions, multilateral agreements, psychological counseling, seal-/tamper-proof devices, and situational crime prevention (Sandler 2011; Lum, Kennedy, and Sherley 2006b).
Target hardening at airports is an example of a defensive counterterrorism intervention that is designed to increase the detection of potential terrorism and deter potential terrorists. Target hardening at airports can be done by placing metal detectors at certain key locations and increasing security screening of all passengers before they board planes. Installing metal detectors and requiring security screening of passengers represent counterterrorism strategies that are visible, identifiable, and known to the public when they enter airports (Dugan, LaFree, and Piquero 2005).
Metal detectors and tighter screening of passengers were interventions implemented in airports throughout the United States beginning in the early 1970s. The measures were put into place in response to a number of domestic and international aerial hijacking events that took place in the 1960s and 1970s.
Practice Theory
The strategy of placing metal detectors at airports and increasing screening of passengers before they board planes has elements of situational crime prevention as well as those of deterrence and rational choice theory. Situational crime prevention focuses on reducing the opportunities for crime, while also increasing the perceived risk of apprehension (Clarke 1983). This can include efforts such as target hardening. Generally, the purpose of target hardening is to make physical entry more difficult or more risky.
Deterrence and rational choice theory holds that humans are rational beings who consider the consequences of their actions and are deterred from engaging in continual patterns of offending as a result of the certainty, severity, and celerity of punishment (Dugan, LaFree, and Piquero 2005). It assumes that individuals weigh the costs and benefits of crime, and therefore crime can be prevented by increasing the costs or decreasing the rewards of committing a crime. Counterterrorism strategies, such as the use of metal detectors, attempt to raise the perceived cost of committing terrorist acts, such as hijacking, by increasing the certainty of detection (Dugan, LaFree, and Piquero 2005).
Additional Information
It should be noted that studies included in the meta-analysis by Lum, Kennedy, and Sherley (2006a), which were assessed for this review, did not examine counterterrorism strategies that have been put into place at airports since 2001, as the authors could not find recent evaluation work.
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Crime & Delinquency | Terrorism and mass violence offenses
Lum, Kennedy, and Sherley (2006a) examined the results from five studies that looked at interventions that increased detection of potential terrorism through airport security (specifically, the studies focused on increasing security of airports in the early 1970s, including the installation of metal detectors and the more general increase in security screening of passengers). With regard to one form of terrorism (hijackings of airplanes), the weighted mean effect size was -6.25, meaning that an increase in airport security led to a statistically significant reduction of approximately 6 hijackings per unit of time. It should be noted that four of the five studies included in this meta-analysis used data between 1968 and 1988. Only one study used data between 1970 and 1996. Therefore, the results may not be generalizable to the security strategies in use at airports today. |
Literature Coverage Dates | Number of Studies | Number of Study Participants | |
---|---|---|---|
Meta Analysis 1 | 1978-2000 | 5 | 0 |
Lum, Kennedy, and Sherley (2006a) conducted a meta-analysis to examine research evaluating the effectiveness of antiterrorism strategies. Studies were included based on three criteria. The first criterion focused on the continuing disagreement over the definition of terrorism. The authors considered any study that referred to the program or outcome as terrorism or terrorism-related, even if the study used a unique, nonofficial, or nontraditional definition of terrorism. The second criterion focused on the definition of interventions. The authors took a liberal approach, and included any study that evaluated the effects of programs generally designed to prevent, detect, manage, and/or respond to terrorism events; related incidents and issues; risk factors; time periods; groups; and/or individuals. The third criterion was related to a measurable outcome of effectiveness. The primary outcome of interest was the number of terrorist incidents, but other outcomes such as the reduction in the public’s fear of terrorism and the decline in the number of terrorist groups, were also included.
A comprehensive search was conducted and a total of 354 documents (including articles, reports, and other published and unpublished materials) were identified for closer examination. From those documents, a total of seven studies satisfied the requirements for inclusion. At a minimum, the studies 1) evaluated two or more units of analysis, comparing some with and without the counterterrorism intervention; 2) made some attempt to provide for controls within a statistical analysis; 3) conducted an interrupted time series or intervention analysis to indicate some temporal ordering of effects; and 4) were not medical studies.
All of the studies used an interrupted time series analysis, or a related approach, to examine the effectiveness of counterterrorism strategies. Each of the studies (except for one) included multiple findings for different interventions, time periods, and/or outcomes. Some of the studies reported evaluating multiple interventions within the same study. Some of the studies evaluated the effects of multiple interventions on different outcomes (for example, the effect of metal detectors on skyjacking, or hijacking of planes, and embassy attacks). Because the studies used interrupted time series analysis, there were multiple findings across different time periods for the same study. For example, one study could have four separate findings if it looked at the short and immediate time frames as well as long or stable time periods.
In total, 86 findings were examined across the seven studies. Of the seven studies, five studies included data on the effects of increased detection at airports (including the installation of metal detectors and increased security screening of passengers). From those studies, 16 findings were examined. The primary outcome of interest for this review was skyjackings or hijacking of airplanes.
The authors noted that meta-analyses conducted on time series data is uncommon, and cautioned readers to be aware that they were making comparisons across different time periods and event categorizations. In addition, the authors noted that readers should be cautious about the time periods included in the studies on metal detectors and increased security screenings at airports. Four of the five studies used data between 1968 and 1988. Only one study used data between 1970 and 1996. Therefore, the results from the meta-analysis may not be generalizable to the security conditions in place at airports today.
These sources were used in the development of the practice profile:
Lum, Cynthia, Leslie W. Kennedy, and Alison J. Sherley. 2006a. The Effectiveness of Counter-Terrorism Strategies: A Campbell Systematic Review. Campbell Systematic Reviews 2.
https://www.campbellcollaboration.org/better-evidence/effectiveness-of-counter-terrorism-strategies.htmlThese sources were used in the development of the practice profile:
Clarke, Ronald V. 1983. “Situational Crime Prevention: Its Theoretical Basis and Practice Scope.” Crime and Justice 4:225–56.
Dugan, Laura, Gary LaFree, and Alex R. Piquero. 2005. “Testing a Rational Choice Model of Airline Hijackings.” Criminology 43(4):1031–65.
Lum, Cynthia, Leslie W. Kennedy, and Alison J. Sherley. 2006b. “Are Counter-Terrorism Strategies Effective? The Results of the Campbell Systematic Review on Counter-Terrorism Evaluation Research.” Journal of Experimental Criminology 2:489–516.
Lum, Cynthia, Leslie W. Kennedy, and Alison J. Sherley. 2008. “Is Counter-Terrorism Policy Evidence-Based? What Works, What Harms, and What is Unknown.” Psicothema 20(1):35–42.
(NIJ) National Institute of Justice. 2011. “Terrorism”. Accessed on June 19, 2015.
https://nij.ojp.gov/topics/articles/research-domestic-radicalization-and-terrorismSandler, Todd. 2011. “The Many Faces of Counterterrorism: An Introduction.” Public Choice 149:225–34.
Targeted Population: Serious/Violent Offender
Setting (Delivery): Other Community Setting
Practice Type: Crime Prevention Through Environmental Design/Design Against Crime, Situational Crime Prevention, Violence Prevention
Unit of Analysis: Places