Overall Study Motivation

Between 2012 and 2015, the number of homicides committed with a firearm increased 12 percent to 12,979 across the 50 U.S. states, Washington, D.C., Guam, and the Virgin Islands (Centers for Disease Control and Prevention, undated-b). Some estimates would put the economic cost associated to this number of firearm homicides at $112.3 billion in 2015 alone, in terms of the psychological, social, and economic loss and damages (Heaton, 2010). In addition to fatalities, firearm violence resulted in more than 20,000 hospital admissions (Centers for Disease Control and Prevention, undated-a), with more than 460,000 nonfatal criminal firearm victimizations in 2014 (Truman and Langton, 2015). Given the magnitude of these damages, it is vital that criminal justice agencies develop programs that reduce the risk of these crimes. Furthermore, local, state, and federal governments have limited resources, so considering the benefit-cost of a program to society compared with other programs can be one way of deciding whether to select a program.

Study Intervention Background

In 2007, the Los Angeles City Attorney’s Office implemented a pilot study of a gun letter intervention to deter straw purchases and other illegal transfers of firearms (such as gifting to a prohibited possessor), and to increase reporting of lost or stolen firearms (Ridgeway et al., 2008). The intervention involved sending a letter to handgun purchasers during their ten-day waiting periods between purchase and taking possession of the firearm, which advised the purchaser that the new weapon was registered to them and that failure to properly record any transfer or loss of the weapon with California’s Department of Justice could result in the owners’ liability for any future misuse of the gun. Because studies show that many people who use a gun in a crime (1) do so with a gun recently purchased from a licensed dealer but (2) acquired the gun through the secondary market or by a straw purchase, the idea of the letter program was to deter legal buyers from transferring the weapon to a prohibited possessor who may use the gun in a crime.

A pilot randomized controlled trial of the letter program was conducted in two neighborhoods of the city of Los Angeles from May 2007 to September 2008 (Ridgeway et al., 2011). Results of the trial indicated people who received the letter were twice as likely to report their gun stolen as those who did not receive the letter. Although no difference between groups was found regarding rates at which guns were recovered at crime scenes, the study follow-up period may have been too short to detect any such effects.

Present Study

Five years after the pilot study, the letter program was fully implemented citywide from January 1, 2013, through September 1, 2015. Letters were sent to all handgun purchasers residing in city of Los Angeles zip codes during the ten-day waiting period. Our study expanded on previous findings of the pilot study by examining the effect of the letters on firearm violence citywide and by conducting a benefit-cost assessment of the letter program.

We used two statistical approaches to assess the effect on firearm violence. First, we used monthly data on the number of reported firearm violence offenses (homicide, robbery, and aggravated assault) from October 2008 to December 2015 and tested whether the introduction of the letter in 2013 fundamentally changed the pattern of firearm violence in Los Angeles. Second, we used the monthly rates of firearm violence in Los Angeles before the letter program (2001 through 2012) and matched Los Angeles to a control group with similar trends in firearm violence. Using this match, we tested whether there was any difference in firearm violence rates between Los Angeles and the control group after the letter program was implemented (2013 and 2014). A number of robustness checks were performed to test the sensitivity of results.

Finally, we calculated the cost of implementing the program over a period for which we have data (March 7, 2014, through September 1, 2015), and compared the costs of the program with the societal benefits of firearm crimes prevented. We also compared the benefit-cost ratio of this program to other criminal justice programs for adults.

Findings

We were unable to detect a reliable citywide effect for the letter program on homicides, robberies, or aggravated assaults with a firearm. The cost of the program was approximately $1.13 to $1.85 per letter, or $145 to $428 per day worked on the program. Considering the cost of the program relative to the societal benefits of preventing victimization, if the program prevents one homicide, one aggravated assault, or two robberies, then the program achieves a net benefit to society. While a statistical analysis would not have been able to identify the prevention of one or two crimes at a citywide level regardless of the true effects, it is also unclear whether the letter program can indeed prevent any firearm violence.

Policy Implications

Attorney’s Offices make decisions about what programs to fund given the effectiveness of programs and limited budgets and staff time. To that end, the letter program was a relatively lowcost program. Given the way that the Los Angeles City Attorney’s Office staffed and operated the program by the end, the opportunity costs were also minimized in such a way that made the program feasible along with the other work that staff needed to perform. However, although it was low cost, this program appeared to have effects on firearms crime too minor to detect using ix our statistical procedures. If an Attorney’s Office has the resources, there are more costly programs that have demonstrated better cost-effectiveness than the letter program (we note some of these in the results section of this report). If, however, an Attorney’s Office is specifically looking for lower-cost programs (approximately $55,000 per year operating cost, not including start-up costs), the letter program appears to be a sensible option.

Another important implication of this study is data-related. It is essential to have data on the guns affected by the program and a group of comparison guns to more definitively determine whether firearm-related strategies are cost-effective. For example, if we had information on the specific guns used in firearm violence as a result of straw purchases, then we could determine whether the letter intervention made it less likely that the affected guns were used in this manner. We were not able to access these data through the Bureau of Alcohol, Tobacco, Firearms and Explosives or California’s Department of Justice for purposes of this study.