There were near mirror-image letters in the Los Alamos Daily Post (link) and Santa Fe New Mexican Thursday claiming that state level background checks are credited with reductions of 46 or 47 percent fewer women shot to death by their partners and 48 or 53 percent fewer law enforcement officers killed by handguns. The problem is, nowhere do the authors of these letters provide sources for this information.
I put the quotes from the letters into a web search and came up with an Everytown For Gun Safety source (there may be others), almost verbatim, with links to details on these categories. When I clicked on these links to see the details, I was treated to “Sorry, we couldn’t find what you’re looking for.”
So I would challenge these letter writers to provide credible and unbiased sources for these numbers and evidence that there is a causal relationship between initiating a background check system and seeing such dramatic reductions in gun crime. So far no one writing these letters has provided such a reality check.
As far as cause and effect, the only study I know of that tried to model a “before and after” cause/effect relationship between gun homicide and gun laws was a paper out of the Bloomberg School of Public Health (Kara E. Rudolph, Elizabeth A. Stuart, Jon S. Vernick, and Daniel W. Webster. Association Between Connecticut’s Permit-to-Purchase Handgun Law and Homicides. American Journal of Public Health: August 2015, Vol. 105, No. 8, pp. e49-e54.). The authors modeled (not proved) that the CT Permit to Purchase law implemented by Connecticut in 1995 was causatively associated with a steeper (~40% over ten years) drop in gun homicides than was seen in CT in non-gun homicides over the same interval or when compared to gun homicides over that same interval in several control states that did not have or implement similar laws. It is a good paper in part because the authors are very careful to identify and discuss their assumptions and try to work in meaningful controls, which is a vexing problem in this field. But the CT case involved a rigorous handgun permit to purchase law in conjunction with background checks, not a background check law alone. So there are major differences here
not only in sociology but law.
As far as criminals like Davon Lymon getting guns, its not as simple as background checks, as the city of Chicago shows. I suggest this paper: Sources of guns to dangerous people: What we learn by asking them. Philip J. Cook, Susan T. Parker, and Harold A. Pollack. Preventive Medicine 79 (2015) 28–36.
So as far as tossing around figures, these need to be taken with a sack of salt. Like the belief that more women were abused on Super Bowl Sunday than on any other day, these numbers may well be an urban legend that has become a “fact” because it has been uncritically spread so often by well-meaning people in the furtherance of their cause. Or perhaps an assumption based on vague advocacy science. Reality is not so cut and dried.
If you are going to quote numbers, please provide a credible reference. If we are to lobby the Legislature of New Mexico to pass more laws, we need to be able to sort the information into what is wheat and what is chaff.