After a gunman murdered 19 children and two adults at an elementary school in Uvalde, Texas, politicians responded as they always do to such shocking crimes. Democrats pushed gun control policies ranging from the symbolic to the flagrantly irrelevant, while Republicans emphasized improvements to school security.

On its face, “hardening” schools so they are less vulnerable to attack seems more logical than banning “assault weapons” defined by functionally unimportant features or expanding the federal background-check requirement for gun buyers, which is ill-suited to deterring mass shooters because they typically do not have disqualifying criminal or psychiatric records. But the approach favored by Republicans has pitfalls that legislators should not ignore in their rush to “do something” about crimes that are horrifying but rare.

To start with the obvious: Even sensible precautions do not work if they are not properly implemented. Although the Uvalde school district had a policy of keeping school entrances and classroom doors locked “at all times,” the shooter entered through an unlocked rear door; the door to the adjoining classrooms where he killed children and teachers was likewise unlocked.

The school district also had the “good guys with guns” who are supposed to thwart this sort of attack: its own police force and armed guards, plus local cops and members of a Border Patrol unit with “an immediate-response capability” for “emergent and high-risk incidents requiring specialized skills and tactics.” Yet it took police more than an hour to confront and kill the gunman — an egregious failure that Uvalde Mayor Don McLaughlin has asked the Justice Department to investigate.

Beyond those specific lapses, we know surprisingly little about the cost-effectiveness of school security measures. “Whatever evidence does exist on this front is mixed, at best,” notes a 2021 RAND Corporation report.

Although safeguards such as metal detectors and surveillance cameras have been widely adopted, the report says, “these technologies’ actual effects on detection and deterrence are unclear or mixed.” A 2016 RAND review of the literature found that surveillance cameras are “more effective at preventing or minimizing property crimes (e.g., vandalism) than at preventing school violence or other crimes at school.”

The evidence concerning “school resource officers” (SROs) is “similarly mixed,” the 2021 report says. “Although some studies suggest that having an SRO present can be an effective approach to reducing school violence,” RAND notes, “others show that an SRO’s presence can degrade students’ perceptions of safety.”

That is not surprising, since conspicuous security measures like SROs may create the impression that students face greater dangers in school than they actually do. There is also a risk that SROs will transform relatively minor disciplinary issues into criminal matters, sometimes with appalling consequences.

“Active shooter” drills raise similar issues. There is little evidence that they enhance safety but ample reason to think they make students feel less safe.

Related Articles

Even strategies that look promising can be prohibitively expensive. In 2019, The Texas Tribune reports, a Texas school district estimated that adding two secure lobbies to a junior high school would cost $345,000.

Before concluding that the answer is more money, policymakers should take a breath and consider the magnitude of the danger they are trying to address. “Since 2013,” Northeastern University criminologist James Alan Fox reports, “77 students in grades K-12 have been killed in 11 school mass shootings,” defined as attacks that injured at least four victims and killed at least one student.

In a country with more than 130,000 K-12 schools, the risk that any particular school will experience such an attack is infinitesimal. As Fox notes, 40 times as many children die in pool drownings each year than are killed with firearms in schools, which remain one of the safest environments for children.

“We beg you,” a group of current and former school principals say in a recent open letter. “Do something. Do anything.” While that impulse is understandable, it can lead to policies that do more harm than good.

Jacob Sullum is a senior editor at Reason magazine. Follow him on Twitter: @JacobSullum.