On the other end of the policy spectrum is Missouri, which had a background-check system before it was repealed in 2007. The Johns Hopkins Bloomberg School of Public Health took a closer look at the impact on public safety in the state after the policy change, and the Washington Post's Niraj Chokshi helped summarize the results.
The law's repeal was correlated with a 23 percent spike in firearm homicide rates, or an additional 55 to 63 murders annually from 2008 to 2012, according to the study conducted by researchers with the Johns Hopkins Center for Gun Policy and Research and to be published in the Journal of Urban Health. "This study provides compelling confirmation that weaknesses in firearm laws lead to deaths from gun violence," Daniel Webster, director of the Johns Hopkins Center for Gun Policy and Research and the study's lead author, said in a news release. "There is strong evidence to support the idea that the repeal of Missouri's handgun purchaser licensing law contributed to dozens of additional murders in Missouri each year since the law was changed."
For context, note that there was no comparable increase at the national level -- in other words, it's not like Missouri saw a spike because everyone nationwide was seeing a spike -- and more to the point, the eight states that border Missouri also did not experience a similar increase.
That said, the states surrounding Missouri were affected.
From Chokshi's report:
Police in border states that kept such laws reported a big spike in guns bought in Missouri that had been diverted to criminals. In 2009, Missouri exported 136 guns to neighboring Illinois and 78 to neighboring Kansas, according to data collected by the Bureau of Alcohol, Tobacco, Firearms and Explosives and compiled by Mayors Against Illegal Guns.
When Senate Republicans killed a bipartisan background-check proposal last year, considered in the wake of the Sandy Hook massacre, one of the more common refrains from opponents of reform was that background checks just don't make a lot of difference. Even if proponents are well intentioned, the process itself is a feel-good measure with little real-world implications.
The data out of Missouri appears to point in a very different direction.