Gun control has no impact on gun deaths.

From California's comprehensive background check and misdemeanor violence prohibition policies and firearm mortality by Alvaro Castillo-Carniglia, et al. From the Abstract:

Purpose

In 1991, California implemented a law that mandated a background check for all firearm purchases with limited exceptions (comprehensive background check or CBC policy) and prohibited firearm purchase and possession for persons convicted within the past 10 years of certain violent crimes classified as misdemeanors (MVP policy). We evaluated the population effect of the simultaneous implementation of CBC and MVP policies in California on firearm homicide and suicide.

Methods

Quasi-experimental ecological study using the synthetic control group methodology. We included annual firearm and nonfirearm mortality data for California and 32 control states for 1981–2000, with secondary analyses up to 2005.

Results

The simultaneous implementation of CBC and MVP policies was not associated with a net change in the firearm homicide rate over the ensuing 10 years in California. The decrease in firearm suicides in California was similar to the decrease in nonfirearm suicides in that state. Results were robust across multiple model specifications and methods.

Conclusions

CBC and MVP policies were not associated with changes in firearm suicide or homicide. Incomplete and missing records for background checks, incomplete compliance and enforcement, and narrowly constructed prohibitions may be among the reasons for these null findings.

Just another study among thousands, but interesting none-the-less. I frequently observe that the suggested gun control policies shrilly advocated for after some tragedy almost never are pertinent to the tragedy itself. In other words, even had the recommended policies been in place, the facts of the case are such that the tragedy would have happened anyway.

That California has among the most stringent restrictions in the nation makes this a notable study. One can conjure all sorts of scenarios why that might be, but it is interesting that that is the fact.

UPDATE: On reflection, I wonder if there might not be a further point of interest to be teased out from this study. America has a higher murder rate than most of our OECD counterparts. However, complicating the analysis, it is also true that the US has the most heterogeneous population compared to all our OECD counterparts. Given America's sheer size, in population and geography, there are simply no real benchmarks with whom to compare.

From other studies, it is observable that America tends to be average when you compare it to individual other countries but when you make the comparison based on culture of origin, the US tends to come out way ahead. Education is the one with which I am most familiar. White Americans outscore all European countries, (usually significantly), on PISA scores other than the Finns on reading. Asian Americans outscore all Asian countries on PISA scores. African Americans outscore all majority black countries on PISA scores.

The same is true of productivity and income.

So while there are differences within America between culture-of-origin groups, all people in America from every other culture do better than their home counterparts when they move to America.

My suspicion is that the same is likely true for the violence. We know that, in rounded numbers, 50% of all murders are committed by African Americans, 25% by Hispanics and 25% by European culture origin Americans despite their corresponding presence in the population of 15%, 15% and 70% respectively. My suspicion is that were you to do a rigorous comparison, one might find that the murder rate for white Americans to be near or lower than that of their European counterparts and the same for African Americans (for majority black countries) and Hispanics (for Hispanic countries of origin).

I have never seen such a rigorous study done but there are all sorts of intriguing snippets that are at least suggestive. While we are rightly dismayed in America about rare but tragic mass school shootings, it is easy to neglect that three or four of the top five global school shootings have occurred in Europe where gun rights are generally much, much more tightly circumscribed.

The overall point is that there are good reasons to believe that cultural dispositions are likely a far greater driver of base rate outcomes than are particular policies. Returning to education as an example, the broad outlines of public school education among the 50 states are reasonably similar. There are always many policy trials and experiments going on in the different states, some small number of which occasionally demonstrate effectiveness and then become widely adopted. That said, there is insufficient variance in policy to explain the consistent differentials in cultural origin differences consistent across the nation.

What we don't know, and would be useful to know, is whether America is inherently violent because of its inherent heterogeneity, because of its Second Amendment, or because of the particular, and evolving, mix of cultural origin disposition towards violence. Were we to conduct such a rigorous study, my suspicion is that we might find that the Second Amendment is far less of a driver of violent death than we have all along assumed.

So if results are driven much more by culture than by policy, it is reasonable to speculate about its impact on the propensity to violence in a state such as California which has long had a strong orientation towards limiting Second Amendment rights. Especially given that California is also the state with the greatest increase in Hispanic emigration (legal and otherwise). In an arena where there is both an increasing constriction on gun rights but also an increasing share of the population with a cultural origin in a culture with a dramatically higher manifestation of violence, perhaps the two are operating at cross-purposes to one another.

A further complicating factor is that California is also the state with among the worst school systems, worst income inequality and the highest rate of population in poverty.

Specifically, in the forty year time frame Castillo-Carniglia, et al are examining, it is conceivable that in fact the gun control laws are in fact effective but that their effect is being swamped by the increase in violent country-of-origin culture, and inequality, and poverty.

All interesting but speculative questions.