How often does legal gun possession prevent crime? If you don’t think it happens very often then you might think a policy of restricting gun rights will lead to greater public safety. The question is difficult to assess because it involves events that rarely get reported—as when a would-be criminal doesn’t commit a crime because he is deterred by the knowledge that a potential target is armed. That point is lost when the question is conflated—as it often is—with the question “What’s more common, crimes committed with guns or justifiable shootings of criminals in the act?”
Despite the inherent opaqueness of the issue, there has been some research on it, which Jim Agresti has rounded up:
[A] range of credible data suggests that civilians use guns to stop violence more than 100,000 times per year.
For instance, the above-cited 1995 paper was based on a survey of 4,977 households, which found that at least 0.5% of households over the previous five years had members who had used a gun for defense during a situation in which they thought someone “almost certainly would have been killed” if they “had not used a gun for protection.” Applied to the U.S. population using standard scientific methods, this amounts to at least 162,000 saved lives per year, excluding all “military service, police work, or work as a security guard.”
Since this data is from the 1990s and is based on people’s subjective views of what would have happened if they did not use a gun, it should be taken with a grain of salt. However, the same survey found that the number of people who used a gun for self-defense was about six times greater than the number who said that using the gun “almost certainly” saved a life. This amounts to at least 1,029,615 defensive gun uses per year, including those in which lives were saved and those of lesser consequence. […]
Anti-gun researcher David McDowall and others conducted a major survey of defensive gun use that was published by the Journal of Quantitative Criminology in 2000. The authors did not take their survey results to their logical conclusions by using the common practice of weighting them to determine what the results would be for a nationally representative survey. But when one does this, the results imply that U.S. civilians use guns to defend themselves and others from crime at least 990,000 times per year. This figure accounts only for “clear” cases of defensive gun use and is based upon a weighting calculation designed to minimize defensive gun uses.
Similarly, a 1994 survey conducted by the U.S. Centers for Disease Control and Prevention [CDC] found that Americans use guns to frighten away intruders who are breaking into their homes about 498,000 times per year.
In addition, notes Agresti, a committee convened by the Institute of Medicine and the National Research Council reported in 2013: “Almost all national survey estimates indicate that defensive gun uses by victims are at least as common as offensive uses by criminals, with estimates of annual uses ranging from about 500,000 to more than 3 million….”
[James D. Agresti, “How Often Do Citizens Use Guns to Stop Violence,” Just Facts Daily, February 23]
