Proponents of metal detectors, such as Philadelphia Police Chief Inspector Cynthia Dorsey, view then as a proactive technique to curb school violence by intercepting and confiscating weapons. For example, Philadelphia school officials recovered six handguns and 31 BB or pellet guns, the philly.com website reported in March 2013. A screening system lets students know they risk suspension, expulsion and police investigation if security officers catch them bringing weapons onto school property
Installing metal detectors also requires hiring and training people to operate them. One example is the New York City Board of Education's program in place at 50 of its inner-city high schools. For one school with 2,000 students, nine security officers are needed for two additional hours every morning, according to a National Criminal Justice Reference Service overview. Districts must also restructure starting times to avoid long waits and scheduling disruptions that make students late for class.
According to the International Foundation for Protection Officers, metal detectors can play a role in a comprehensive school security strategy. The purpose of metal detectors is to find guns, knives or other forbidden objects before a student harms peers or employees with them. The foundation's analysis indicates that security experts recommend combining use of metal detectors with other measures -- such as implementing anti-bullying initiatives, controlling access to school buildings, installing closed circuit video systems, and training staff to recognize threatening behavior.
Critics argue that an overreliance on physical security measures like metal detectors breeds complacency and unrealistic expectations. Many shootings and other violent incidents happen outside of school buildings, as National School Safety and Security Services president Ken Trump observes, in an analysis posted on his organization's website. Also, parents often don't realize that metal detectors can be compromised by faulty equipment, failure to follow policies, or inconsistent operating procedures.
The National Association of School Psychologists contends that the introduction of metal detectors may backfire by creating a militarized environment that stigmatizes students as violent and untrustworthy, while doing little or nothing to ease their fears of crime. Such measures also feed public perceptions of schools as inherently dangerous places. Student social interaction is also more likely to suffer, since the use of metal detectors often accompanies strict discipline measures, the association argues.