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Study links permissive state gun laws to higher rates of mass shootings

Emanuel African Methodist Episcopal Church
REUTERS/Charleston Police Department
Police, ambulance and fire crews are pictured outside the Emanuel African Methodist Episcopal Church following a shooting incident in Charleston, South Carolina, in this June 17, 2015, photo. Nine parishioners were killed during a prayer service.

States with permissive gun control laws and higher rates of gun ownership tend to have more mass shootings, according to a study published this week in the BMJ.

The study also found that the gap in mass shootings between states with weak gun laws and those with tough ones has widened in recent years.

“Our analyses show that U.S. state gun laws have become more permissive in recent decades, and that a growing divide in rates of mass shootings appears to be emerging between restrictive and permissive states,” write the authors of the study.

Previous research has shown that states with lax gun laws tend to have higher rates of homicides and suicides involving firearms. Studies have also have linked higher rates of gun ownership with greater numbers of gun assaults and homicides.

But it hasn’t been clear how state gun laws and gun ownership influence mass shootings.

The authors of current study, a team of researchers at Columbia University’s Mailman School of Public Health, set out to explore that issue.

Digging through the data

For the study, the researchers used 1998 through 2015 editions of “Traveler’s Guide to the Firearms Laws of the Fifty States,” which gun owners refer to when traveling across state lines. The guide rates the gun law strictness of each state on a scale from 0 (completely restrictive) to 100 (completely permissive).

Scores are based on 13 factors, including whether state residents have the right to carry guns in the open, whether the ownership of semi-automatic rifles and machine guns is limited, and whether out-of-state gun permits are recognized.

To determine the number of mass shootings in each state, the study’s researchers also used data from the FBI’s Uniform Crime Reporting program. The FBI defines a mass shooting as an event in which four or more people were killed by a firearm.

For their analysis, the researchers also divided the mass shootings into two categories: domestic (incidents in which the perpetrator shot an immediate family member or partner) and non-domestic (all other incidents).

Florida, where the mass shooting at Marjory Stoneman Douglas High School occurred last year, was the only state not included in the analysis because it does not participate in the Uniform Crime Reporting program, according to the study’s authors.

Gun ownership data is not available for all 50 states, so for that statistic the researchers relied on a commonly used state-level measure of how many residents own firearms in any particular year: the percent of suicides committed with a firearm.

Key findings

The study found that gun laws became more permissive overall during the period from 1998 through 2014 — by an average of 0.16 points per year on the “Traveler’s Guide” scale.

Massachusetts was found to have the most restrictive gun laws, while Vermont had the most permissive. (Individual state rankings are not listed in the published study, however.)

The study also identified 344 reported mass shootings between 1998 and 2014. Of those 81 were domestic and 263 were nondomestic.

On average, states with more permissive laws and greater gun ownership tended to have more mass shootings — trends that gained strength from 2010 onward.

Specifically, each 10-point relaxation in a state’s gun laws was associated with a 9 percent higher rate, on average, of mass shootings in that state. And each 10 percent increase in state gun ownership correlated with a 35 percent higher rate of mass shootings.

“This means that a state like California, which has approximately two mass shootings per year, will have an extra mass shooting for every 10 unit increase in permissiveness over five years,” the study’s authors write.

“It will also have three to five more mass shootings per five years for every 10 percent increase in gun ownership,” they add.

The results were the same whether or not someone in a close relationship with the victims committed the shootings.

Limitations and implications

This study was observational, so it can’t prove a direct relationship between state gun laws, gun ownership and mass shootings.

In addition, the restrictiveness-permissiveness score used in the study hasn’t been scientifically validated.

As Paul Reeping, the study’s lead author and a graduate student at Columbia University, told Newsweek reporter Kashmira Gander, “It’s hard to be 100 percent certain that what we found isn’t possibly because states that experience more mass shootings in turn change their gun laws, or some other factors that we just couldn’t measure. However, we did include multiple state-level factors that we could measure — education, poverty, incarceration rate, etc. — and took into account a time lag to limit the reverse effect of mass shootings influencing state gun laws across a 15 year period.”

Still, the study’s findings can’t be dismissed, particularly as they support previous research that has linked gun-law permissiveness and gun ownership to other types of gun violence.

Just last year, researchers reported that gun deaths among children and teens are twice as common in states with the most lax gun laws.

Reeping and his co-authors say there is an urgent need for better data collection and more research into the effect of gun laws on gun deaths in general and mass shootings in particular.

“Domestic violence and suicide are commonly connected to mass shooting events, so state gun laws involving restraining orders and extreme risk protection orders may be valuable first opportunities for scientific evaluation,” they point out.

Meanwhile, such events continue to claim American lives. Since January 1, at least 39 people have died in eight separate mass shootings.

FMI: The new study can be read in full on the BMJ website. (The BMJ was formerly known as the British Medical Journal.)

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Comments (24)

  1. Submitted by Ray Schoch on 03/08/2019 - 10:40 am.


    There are, literally, dozens of academic studies examining one or more aspects of the issue the study Susan is writing about tries to get at. There are even more newspaper and magazine articles based on informed opinion. Hundreds of books have been written, and, I’d guess, thousands of speeches given by everyone from politicians to gun violence victims. They will be, and usually are, dismissed by the paranoia of gun-rights true believers, assisted by campaign contributions from a variety of sources that include gun manufacturers protecting their own profits, and by editorial content in numerous magazines that are essentially elaborate advertising for those gun manufacturers.

    It’s true that observation is not causation, but it often does provide a large, flashing red arrow pointing toward where logic should take a thoughtful person’s conclusions.

  2. Submitted by richard owens on 03/09/2019 - 11:18 am.

    …from the study:

    “What is already known on this topic

    More permissive state gun laws and higher levels of gun ownership are associated with higher levels of gun homicide and gun suicide in the US

    What this study adds

    States with more permissive gun laws and greater gun ownership have higher rates of mass shootings

    There is a growing divergence in recent years as rates of mass shootings in restrictive states have decreased and those in permissive states have increased”
    [end quote]

    Those conclusions do not require much of a leap– responsible legislatures and community leaders must work to reduce the “permissible” factors in their gun policies and work toward more restrictive policies if we are to address the rise in mass shootings that accompany a rise in permissiveness policies.

    Reasonable gun owners would agree- we have had quite enough of the expanding of “gun privileges” pushed by the GOP, the NRA and ALEC.

    The data speaks the truth.

  3. Submitted by Kent Fralish on 03/09/2019 - 01:05 pm.

    “Gun ownership data is not available”.
    That in itself throws the whole thing in the trash.

    • Submitted by richard owens on 03/10/2019 - 10:16 am.

      Mr. Fralish: Your quote “Gun ownership data is not available.”

      The article ACTUALLY says, “Gun ownership data is not available for all 50 states, so for that statistic the researchers relied on a commonly used state-level measure of how many residents own firearms in any particular year: the percent of suicides committed with a firearm.”

      Your suggestion of trashing the study dismisses some scientific work, documented and peer reviewed.

      The study seems to draw well-supported conclusions. The methodology too seems rigorous and seeking. Reasonable people will respect this kind of significance if we are to have a common set of understandings with which to make political decisions.

      The risk factors learned in this study demonstrate a need for more restrictive gun laws. The data were adjusted to NOT use incomplete or unsupported data, and historical data was used to show trends.

      It is definitely not “trash”. It should be considered illuminating to those who actually are sick of the death and destruction commensurate with more indiscriminate gun distribution and weak regulation of it.

  4. Submitted by Steve Rose on 03/10/2019 - 03:16 pm.

    About this time last year, ABC’s WJLA published this report


    “One of the top ten states with the most restrictive gun laws in the country is Illinois, where last year there were 650 murders in Chicago alone, according to a USA Today’s compilation of crime data.

    In Maryland, another state with some of the strictest gun laws in the country, Baltimore had 343 murders last year and has highest per capita murder rate in the nation. The city was also just named the most dangerous city in America by USA Today.”

    • Submitted by richard owens on 03/10/2019 - 05:10 pm.

      From your piece (a TV station in West Baltimore)

      Leon Pinkett is a city councilman in West Baltimore, an area with one of the highest rates of violent crime.

      “I represent a community that doesn’t just experienced trauma, we live in trauma. These guns aren’t licensed they aren’t permitted, there are no background checks they were never purchased legally,” Pinkett said in an interview Tuesday.

      But Pinkett still believes stricter gun laws would help.

      “We need to be looking strongly at permitting, licensing, and stricter background checks mental health and even should we be banning assault weapons,” he said.

      • Submitted by Steve Rose on 03/11/2019 - 07:22 am.

        Says a council man in a state and city (Baltimore, MD) with some of the most restrictive gun laws:

        “These guns aren’t licensed they aren’t permitted, there are no background checks they were never purchased legally,” Pinkett said in an interview Tuesday.”

        But Pinkett still believes stricter gun laws would help.

        Really? Perpetrators are using guns “never purchased legally”, but more laws will help? The laws will help perpetrators that prefer unarmed victims.

        • Submitted by james herzog on 03/15/2019 - 07:35 am.

          Gun proponents say any laws will only benefit criminals because criminals do not follow the law. In other words, gun proponents say no laws are worthwhile, so the logical outcome is tyranny and lawlessness will be the preferred state of society — then their guns will be very important, and so will they — it is clearly some sort of teenage immature fantasy which gun manufacturers and others promote via their advertising, movies and the media, and the result is we must all pay the price of mass murder. Just look at their advertising, it is exactly that.

          • Submitted by Steve Rose on 03/17/2019 - 06:09 am.

            Really, the outcome on no laws is tyranny? Are you acquainted with the definition?
            “noun, cruel and oppressive government or rule.” Tyrannical governments disarm the citizenry’s and hold absolute power.

            It is entertaining to hear descriptions of fantasies ascribed to others – it is a fantasy within a fantasy.

  5. Submitted by richard owens on 03/10/2019 - 05:29 pm.

    What if we don’t restrict guns and we end up escalating the violence?

    In the 60s some rejected MLK’s non-violence, and eventually considered their own right to open carry (remember the Black Panthers?)
    Violent threat begets violent threat- but it is totally predictable.

    (This 5 min video clip coincidentally today BBC news:)

    “Are these America’s least likely gun owners?
    The number of hate crimes against minority groups has risen over the past three years, leading some to take up weapons for their own protection.

    The BBC’s Megha Mohan went to California to find out if the the minority gun owner could become the new norm.

    Video Journalist – Jack Slater

    10 Mar 2019

    • Submitted by Steve Rose on 03/11/2019 - 08:40 am.

      Hate crimes seem to be subject to the market forces of supply and demand. When the supply is insufficient, faux hate crimes increase to satisfy demand. As Aristotle famously stated, “nature abhors a vacuum”

      “Hate crime hoaxes, like Jussie Smollett’s alleged attack, are more common than you think”

      “In writing a book about hate crime hoaxes, I found more than 400. Such frauds damage good race relations.”

      • Submitted by richard owens on 03/11/2019 - 10:09 am.

        This article is about a scientific study that has real credibility well beyond your anecdotal and unsubstantiated hearsay.

        I think you missed the point on the “leftist” new gun enthusiasts. I especially was moved by the Black man’s remarks. He made it clear he did not want a cop thinking he had a gun, but he definitely wanted a neo-nazi to think he was carrying.

        It is escalation of a problem due to the fact that the one entity that benefits (gun makers and dealers) has sabotaged all attempts at fixing it.

        The GOP and ALEC likewise will tolerate any number of innocent deaths to keep their products selling.

        Nobody can force you to care. The tragedy must somehow become real to you before you will see it as something against you personally.

        • Submitted by richard owens on 03/11/2019 - 11:14 am.

          “something OTHER THAN against you personally..”


        • Submitted by Steve Rose on 03/11/2019 - 11:30 am.

          Did you read Susan’s column?

          An excerpt, under the bold subtitle “Limitations and implications”:

          “This study was observational, so it can’t prove a direct relationship between state gun laws, gun ownership and mass shootings. In addition, the restrictiveness-permissiveness score used in the study hasn’t been scientifically validated.”

          To you it is science; to me it is “the study hasn’t been scientifically validated.”

      • Submitted by RB Holbrook on 03/12/2019 - 01:56 pm.

        He found over 400 hate crime hoaxes, over what time period? No, he doesn’t tell us that. One year? Two years?

        In contrast, the author of the piece you cite says that there are about 7000 hate crimes reported to the FBI every year.

        • Submitted by Steve Rose on 03/12/2019 - 08:25 pm.

          No one would argue that fake hate crimes are outnumbered by real ones. Nonetheless, the popularity of hoax hate crimes is peculiar. This topic is examined by Professor Wildred Reilly in a book published just a couple weeks ago titled, “Hate Crime Hoax: How the Left is Selling a Fake Race War”

          From the publisher, “If you believe the news, today’s America is plagued by an epidemic of violent hate crimes. But is that really true?”

          “In Hate Crime Hoax, Professor Wilfred Reilly examines over one hundred widely publicized incidents of so-called hate crimes that never actually happened. With a critical eye and attention to detail, Reilly debunks these fabricated incidents—many of them alleged to have happened on college campuses—and explores why so many Americans are driven to fake hate crimes. We’re not experiencing an epidemic of hate crimes, Reilly concludes—but we might be experiencing an unprecedented epidemic of hate crime hoaxes.”

          • Submitted by RB Holbrook on 03/13/2019 - 04:33 pm.

            I’m still less than convinced.

            “In Hate Crime Hoax, Professor Wilfred Reilly examines over one hundred widely publicized incidents of so-called hate crimes that never actually happened. ”

            So he’s examining 100 out of how many incidents, and those 100 have already been proven to be false. That statistic fails even the most basic test for believability.

            • Submitted by Steve Rose on 03/17/2019 - 03:06 pm.

              That is not a statistic. I am not convinced either, as the book was just released and I have not read it. Having not read it, why so quick to dismiss it? Could it be an issue of confirmation bias?

  6. Submitted by Curtis Senker on 03/11/2019 - 09:16 am.

    There are, literally, dozens of academic studies examining one or more aspects of the issue the study Susan is writing about tries to get at.

    True statement. And anyone on either side of the argument can find one to back them up, because it’s all statistics, and we all know how malleable numbers are.

    I don’t get too worked up about this issue any more. Our right to bear arms is guaranteed by the Constitution. It’s a right the founders saw as being so important they put it in 2nd; right after guaranteeing our right to complain about it.

    So complain away. Pull out your research…None of us will live to see the day the 2nd Amendment is rescinded.

    • Submitted by richard owens on 03/11/2019 - 10:15 am.

      The work was peer-reviewed and based on accepted methods used in many statistical studies.

      Rejection of science means serious people do not need to take your viewpoint seriously, but worse, it means you can’t even agree on a closer definition of the scope and trends of the problem.

      There IS a problem, and if you aren’t seeking a solution, you are part of the problem. The Gun Industry and its apologists will never help, but those whose income does not require more and more unregulated firearms distributions should see the nightmare families so affected face.

      I hope that would be you and all family men everywhere.

      • Submitted by Curtis Senker on 03/11/2019 - 04:41 pm.

        Sadly, peer reviewing is no longer a guarantee of sound research. There are many instances where bad work has withstood review (and, remember the cell phone radiation/brain cancer scandal?). Financial gain, sloppy work and bias all play a part.

        Also, I didn’t say this particular study was sloppy, or incorrect. I said that people on both sides of the argument have access to a plethora of statistical research papers to support their argument. And, although you’ll never see one that argues against more regulation here, they do.

        The problem is some people have firearms that shouldn’t, and the demographic that accounts for the overwhelming majority of stranger killings is politically untouchable. None of the regulations being pushed by 2A foes will do anything to change that.

        California, for instance, has a universal background check law; it has had zero effect.

        In addition, the so-called “red flag” laws open a Pandora’s box of problems, not the least of which is the fact that people, being what they are, are all too often willing to use the legal system to punish people for purely vindictive reasons.

        Mentally ill persons are already prohibited from possessing firearms; it’s a question asked on the background check form every legal gun dealer is mandated by law to have customers fill out.

  7. Submitted by Tom Anderson on 03/14/2019 - 11:04 pm.

    344 mass shootings over 16 years is 21.5 mass shootings per year, less than one per state per year. Wouldn’t even one mass shooting result in a 50, 60, 75, 100% increase in a given state? I’m not disagreeing with the study or the data, but it seems that with such small sample sizes that a lot of factors could skew results rather easily.

  8. Submitted by Dennis Wagner on 03/15/2019 - 11:39 am.

    There is only one thing for sure, any study no matter how factual or not, will be repudiated by the I need to have my gun crowd. Their defense has been and will be continued irrational discussion because owning a killing device is all about emotion and not about rationale thinking. They fear life W/O a killing device close at hand, to protect them from all those burglars etc. valid or not. Seems, Kill or be killed is entrenched in their psyche and nothing is going to change that.

    • Submitted by Steve Rose on 03/17/2019 - 06:32 am.

      “Their defense”, “they fear” are arguments that polarize the discussion. What if instead you stuck to what you think? Make a lucid case for your position.

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