Access to Assault Weapons Amplifies Pre-existing Risks of Violence

The following is a guest post by New York University political scientist Oeindrila Dube.


On October 23rd, 2010, gunmen mowed down 14 youth and injured 12 others at a teenager’s birthday party in Ciudad Juárez, Mexico. How is this related to Friday’s tragic killings at Sandy Hook Elementary School? First, both involved the use of semi-automatic weapons bought in the United States. Three of the guns in the Juárez killings came from the U.S. through its failed gun-tracking program, Operation Fast and Furious.  Second, both show how access to military-style guns can escalate homicides in volatile contexts where there is some underlying demand for these lethal weapons.

My recent working paper  (“Cross-Border Spillover: U.S. Gun Laws and Violence in Mexico”) with Arindrajit Dube and Omar García-Ponce directly examines this idea.  Yesterday, Eric Voeten summarized one finding from an earlier version of the paper: the 2004 expiration of the U.S. Federal Assault Weapons Ban (FAWB) fuelled more killings and gun seizures in Mexican municipios located closer to the states that started selling these weapons –Texas, Arizona and New Mexico. The rise in gun-related killings accounted for about 30% of such murders in the two years after the ban was lifted.

We also find that not all areas were affected equally: the FAWB expiration led to much larger homicide spikes in areas that were unstable in the context of the Mexican drug war.  Informal agreements between drug cartels and local politicians disintegrated as a result of Mexico’s democratic transition, creating cartel destabilization as a by-product in some areas.  Consistent with this account, we detect much larger homicide increases in municipios that were more electorally competitive prior to 2004. And, these effects were larger still in high nacro-trafficking areas.

The general lesson is that access to arms amplifies underlying risk factors in translating guns into violence.  We can draw on this lesson for understanding the gun-crime relationship in a variety of contexts.  What changes is simply the relevant risk factor. It may be cartel instability in Mexico; another possibility is mental health related instability within a given American community, where the presence of high-powered weapons translates a disturbed individual into a killing spree.  Other communities may be at risk due to economic downturns, or the existence of gangs, etc…

Social science research has the capacity to identify some of these factors, and partly predict where military-style weapons are likely to exert the greatest damage.  But predicting whether guns will trigger killings remains a gamble, and an especially uncertain one for communities with un-diagnosed risks.

Greater gun control is one means of eliminating this gamble. The results in our paper directly imply that re-instatement of the assault weapons ban will help curb criminal homicides south of the border.  (After all, 90% of the crime guns seized in Mexico are traced back to the U.S., according to a 2009 GAO report .) But the general lesson distilled also suggests that these restrictions are likely to reduce tragic shootouts among the most vulnerable communities closer to home as well.

13 Responses to Access to Assault Weapons Amplifies Pre-existing Risks of Violence

  1. RobC December 18, 2012 at 9:35 am #

    Greater gun control doesn’t eliminate the uncertainty of whether guns will trigger killings, it simply constitutes a policy change taken despite the uncertainty of prediction. Which is perhaps fine and good, but let’s not pretend it would be anything other than a shot in the dark.

  2. Mark December 18, 2012 at 10:24 am #

    I am not opposed to reinstating the assault weapons ban but facts are important here:

    1) The 90% reference is incorrect. The number is actually 17% of weapons found at crime scenes have been traced back to the US. Mexican authorities screen weapons found at crime scenes and submit a subset of them to the US for tracing when they think the US may have been the origin. 90% of the submitted weapons were traced to the US. My unsubstantiated guess is that the overall number is something higher than 17% but it is incorrect to say it has been established as 90%.
    2) It would have helped if Holder’s DOJ had not flooded Mexico with large numbers of untracked weapons from the US – weapons that the Mexican government documented were connected with hundreds of murders in Mexico.

    • Crash December 18, 2012 at 12:50 pm #

      True. It probably also would have helped if W hadn’t ended the assault weapons ban in the first place and his DOJ hadn’t allowed hundreds of other weapons to make their way into Mexico.

      • Mark December 18, 2012 at 3:02 pm #

        I hate to be in the position of defending Bush 43 but I guess someone needs to as there has been a deliberate attempt to confuse the Bush and Obama programs. The Bush program involved tracking the weapons and was done with the knowledge of the Mexican gov. It was terminated and then for reasons I still don’t understand the current Admin started a program without tracking or informing the Mexican gov which is what led President Calderon to upbraid President Obama at the most recent NAFTA summit.

    • John December 18, 2012 at 7:23 pm #

      1) I have seen no evidence that the reason some guns recovered in Mexico are not submitted for tracing is because Mexican authorities don’t think they come from the U.S. Many are not submitted because tracing information has been destroyed on the firearm – not an indicator that it was obtained outside the U.S. There were also bureaucratic and technical reasons that some Mexican law enforcement units did not have the capacity to participate in the tracing system.
      2) True, but it’s also true that the approx. 2,000 weapons sold legally under Fast and Furious is a small portion of the nearly 100,000 firearms recovered in Mexico and traced from 2007 through 2011, 68,000 of which were purchased on the U.S. commercial market.

  3. Sverrir December 18, 2012 at 3:27 pm #

    The Assault Weapons Ban was full of loopholes though and semi-automatic weapons were accessible – why would the repeal of the Assault Weapons have such a massive effect on violence in Mexico given that?

  4. Wonks Anonymous December 18, 2012 at 5:47 pm #

    The 17% figure doesn’t seem to be precisely right either, puts it at more like 36%:

    • Mark December 18, 2012 at 6:59 pm #


      Looking at your article and others I agree that 17% is too low though hard to tell what it is precisely which I guessed was the case above. Thanks for the link.

  5. Dave December 20, 2012 at 1:00 am #

    I’ve heard that there were substitute goods for the types of guns banned by the assault weapons ban, that the ban was mostly about cosmetic appearances of weapons and not their deadliness. Is this true? Or is this just something pro-gun people say?

  6. Joe McDaniel December 22, 2012 at 2:32 pm #

    The assault weapons ban was purely cosmetic banning flash suppressors and large magazines. The AR15 is not an assault weopon — it just looks like the M16 which is an automatic rifle.

    My feeling is we need something like the Fire Arms Certificate of the UK and Canada. Also, how about the airplane cockpit solution for schools — provide a door that is not breachable with ease.

    • Calamity January 7, 2013 at 7:24 pm #

      Interesting ideas, Joe. Another consideration: One security expert talked about an addition to glass that would render it more bullet resistant (no such thing as bullet proof). Not sure if this is the same thing, but . . . “Some security companies offer “one-way bullet-resistant glass”, designed to stop incoming bullets, while giving the person on the inside the option to shoot back.”

  7. Nick January 6, 2013 at 1:33 pm #

    you give me a teacher in a room full of children with a locked safe with a gun, an intruder intent on killing people with a semi-auto weapon… and I’ll show you a picture of a room full of dead children, a dead teacher with the key to the safe still in his/her hands…

  8. Quinn March 5, 2013 at 3:11 am #

    The law also banned control of illicitly imported or contrived firearms, but did not ban tenure or sale of pre-existing assault weapons or before plant standard magazines that were lawfully redefined as large ability bullets feeding strategy. This condition for pre ban firearms shaped higher prices in the souk for such substance, which still survive due to some states adopting their own assault weapons bans.