APRIL 22, 2012 10:52PM

“Stand Your Ground”: How does it stand up to history?

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In my two previous posts (here and here) on Florida's "Stand Your Ground" law, I discussed the results of various (and relatively simple) before-after analyses I did using observational data. These data included the number of justifiable homicides, the total number of homicides and the number of homicides involving a firearm for the State of Florida. I also included national data on homicides to help refine the predicted values for some of these analyses. The results seemed to show that a significant increase in homicides involving firearms as well as justifiable homicides was observed after the enactment of Florida Statute 776.013 (3) in 2005.

Using a before-after study methodology can be tricky. You see, one of its primary assumptions states that external factors influencing the number of events (i.e., motor vehicle crashes, deaths, suicides, etc.) remain constant or unchanged for the entire study period (both for before and after periods). They usually cannot be all eliminated, but when they are known, the study design needs to be changed in order to minimize potential biases associated with the proposed analyses.

For this short post (I promise!), I therefore decided to focus my attention on these external factors. In order to accomplish this task, I extracted information about when specific laws and regulations related to gun control were introduced or enacted by the federal government between 1980 and 2010. I didn't have the time to find the same information for state and local regulations, particularly those enacted in Florida (other than the SYG law). It is therefore possible that some of these could have influenced the annual number of homicides, but I remain confident that their impacts are minor.

The primary Acts and pieces of legislations are tabulated below:

Relevant Gun Control Legislations Enacted Between 1980 and 2010 (source: http://www.infoplease.com/spot/guntime1.html#1990)

Figure 1

I again focused my investigation on Florida and the U.S. For this one, I used this nifty website to extract the data I needed to produce the figures below; it contained more years of data than the two websites I used previously.

Now, let's see how the number of homicides varies over time as a function of when the various Acts were introduced. I included the average number of homicides for each time period for discussion purposes.

Figure 2

Annual Homicides in Florida

(source: http://www.disastercenter.com/crime/flcrime.htm)


Figure 3 

Annual Homicides for the U.S.

(Source: http://www.disastercenter.com/crime/uscrime.htm)

The figures above show very interesting results:

1) For both datasets, a very wide variation in homicides can be seen prior to the full application of the Brady Handgun Violence Prevention Act in late 1998 via the deployment of the NICS by the FBI. Afterwards, the variation around the mean becomes much much smaller (the coefficient of variation is in fact reduced by a factor equal to 2.5).

2) The Acts introduced in 1994 seemed to have started reducing the number of homicides in Florida and elsewhere in the U.S. Not many studies have examined the effects of the Brady Law, but those I found indicated a reduction in the number of crimes and/or homicides (see list below). Some reported a reduction in the number of suicides.

3) The "jump" seen between 2005 and 2006 in Florida is significant, as discussed before. In fact, the difference between the mean values is more than 6 times the standard deviation calculated for the 1999-2005 time period. This difference is beyond the random variations for observational data (usually below 3 standard deviations).

4) The time period I used for the before-after analyses appears to be adequate. All the analyses were done after 1999.

A sample of studies on the Brady Handgun Violence Prevention Act (and background checks):

Bowling, M., Frandsen, R.J., Lauver, G.A., Boutilier, A.D., Adams, D.B. (2010)  Background Checks for Firearms Transfers, 2009-Statistical Tables. Office of Justice Programs. U.S. Department of Justice. Washington, D.C. (http://bjs.ojp.usdoj.gov/content/pub/html/bcft/2009/bcft09st.pdf)

La Valle, J. M. (2010) Re-Estimating Gun-Policy Effects According to a National Science Academy Report: Were Previous Reports of Failure Pre-Mature? Journal of Crime and Justice, Vol. 33, Issue 1, pp. 71-95.

Frandsen, R.J. (2010) Enforcement of the Brady Act, 2008: Federal and State Investigations and Prosecutions of Firearm Applicants Denied by a NICS Check in 2008, St. Louis, MO: Regional Justice Information Service.

Sumner, S.A., Layde, P.M., Guse, C.E. (2008) Firearm Death Rates and Association with Level of Firearm Purchase Background Check. American Journal of Preventive Medicine, Vol. 35, Issue 1, pp. 1-6.

La Valle, J.M.  (2007) Rebuilding at gunpoint: A city-level re-estimation of the brady law and RTC laws in the wake of Hurricane Katrina. Criminal Justice Policy Review, Vol. 18, Issue 4, pp. 451-465.

Center to Prevent Handgun Violence (2000) Saving Lives by Taking Guns Out of Crime: The Drop in Gun-Related Crime Deaths Since Enactment of the Brady Law.


Thanks to Mishima666 for providing the link to the data I used above as well as for the useful discussions we had on this topic.


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How dare you try to cloud the issue of gun control with salient facts! The fact that American stands far and above the rest of the western industrialized countries in gun deaths per capita ought to be sufficient to make the case for reasonable gun laws. But sad to say, in this case, facts simply don't matter -- NRA lobbying power is all that matters.

I'm afraid that I have some rather awkward questions to ask......

1-: What percentages of the gun crimes mentioned were perpetrated by law enforcement or protective officers?

2-: What other laws were passed at or around the same time as those laws you've mentioned as being influential?

3-: Was there any important social disruption during this time which might have influenced its outcome?

Please understand that I am NOT an NRA member or sympathizer of any kind. I genuinely would like to know the answers to those questions. I think that such answers would make your position very strong indeed by not leaving it open to being attacked from that direction. I openly admit that I am neither a "believer" nor a "denier" in your anti-gun stance. I don't ask awkward questions so as to embarrass you, but to get answers.
Tom: Thank you! When I was looking inot the Brady Law, the NRA was, as expected, against it.

skypixieo: Good questions and I'll get back to you as soon as I can.
Kanuk, your problem is pretty much what mine is: The stats and rationality don't matter in the face of an ideology/mindset that celebrates a gun culture. I grew up with -- and for many years (appropriately) used -- firearms of all types. Then I grew up.
Skypixieo: No problem for asking the questions.

1-: What percentages of the gun crimes mentioned were perpetrated by law enforcement or protective officers?

I don’t know the percentage, since I didn’t look into. I extracted data that are available to everybody on various websites. As far as I know, these data don’t include police shootings, unless the police officer was charged with the homicides. If someone is willing to pay me, I’ll be happy to go deeper in the data. :-)

2-: What other laws were passed at or around the same time as those laws you've mentioned as being influential?

I mentioned this because I read one or two papers that described how local enforcement agencies used different approaches to screen applicants who applied for a concealed weapon permits or something like that. This impacted the crime or violence rates in the county. Thus, there are probably some minor variations like this I cannot account for.

3-: Was there any important social disruption during this time which might have influenced its outcome?

I don’t know, but I don't remember hearing anything like that at the time. If I find something out, I’ll let you know.

Whether or not you’re a member of the NRA doesn’t matter to me.

Boanerges1: Thank you. I agree with your statement.
What Tom said.

Guns are a religious fetish to Americans...who seem to be getting crazier and crazier as the economy (and their wars) are not going their way. At a time when in many areas we need common sense and intelligence we get, instead, religious mania ('religious' in the broadest sense - tho in the narrow sense too!)

I was just reading on Huff how the governor of (wouldn't you know) Mississippi has declared that Democrats' "one mission in life is to abort children". All this madness cannot end well...esp. in a society with so many guns...
Kanuk, It would be great to live in a world with no homicides at all. It would stand to reason that justifiable homicides would be up as more people arm themselves. And it is totally logical that some of those justifiable homicides may have been avoided if neither parties had a gun. The altercation may have ended in both parties walking away or an assault using fist not resulting in death. Or maybe less people are getting away with violent crimes that may have gone unreported or punished because the weaker party prevailed over the aggressor. I have no idea either way.

There are about 2 million rapes, murders, and serious assaults a year. Of those violent crimes about 550,000 where committed with a gun. It is estimated between 500,000 and one million crimes are prevented each year by private citizens with guns. Most incidents do not require discharging the gun. All these numbers show me is:
1. Violent crime touches about 1.5% of the total population
2. Guns are used in .125% of the time
3. Guns prevent more crimes than are committed with guns.
4. All those numbers mean dick if someone is pointed a gun at you or beating you senseless or raping your wife because you are now that statistic. Given the choice I would rather be part of the justified homicide statistic than the victim one.
M Todd: Yes, I agree that it would be nice to live in a world without homicides and crime. However, we all know that human nature/behavior won’t allow us to live in such crime free society. Furthermore, I don’t believe one bit that carrying/owning a gun prevent crimes no matter what the author of “More Guns, Less Crimes” says (which I tear apart his “thesis” very easily). When I have the time I’ll write another post, which will describe the changes associated with violent crimes, such as aggravated assault, forcible rape and robbery among others. You’ll be surprised by the results.

As I said before, the issue is whether or not a higher prevalence of firearms leads to more (unnecessary) murders/injuries than having fewer guns. The figures above show that when firearms are removed for a portion of the population (after 1998), the number of homicides clearly goes down. Obviously one can still kill somebody with their bare hands, but would the murder and attempted murder rates would still be as high? As an example: would these people living in Arizona, a SYG state since 2006, below still be alive if the perpetrator was bare handed?

Unstable ground: The fine line between self-defense and murder

Border Vigilante With Political Ties Dead in Murder/Suicide

Here are some interesting statistics (latest available):

England/Wales (very strict firearm control): 636 homicides* / 55M people = 1.15 E-05
Canada (more strict than US, but much more loose than UK): 554 homicides/ 34M people = 1.62 E-05
US: 14,748 homicides / 309M people = 4.77 E-05

Ratio US/UK= 4.1 times less likely to be murdered in the UK.
Ratio US/Canada= 2.94 times less likely to be murdered in Canada.

*Most are caused by a sharp instrument.

You should check this one out:

Crime statistics for England & Wales: what's happening to each offence?
Here’s additional information:

Canada (without firearms): 384 homicides / 34M people = 1.12 E-05
US (without firearms – 2009 data): 6,095 / 309M people = 1.97 E-05

Over 9,000 Murders by Gun in US; 39 in UK

New Zealand, where police officers usually don’t carry firearms during patrol:

In 2008, there were 70 homicides (7 by a firearm!).

Rate: 70 homicides / 4.2M people = 1.67 E-05

We’re still far from the US homicide rate…

Not to seem callous, but if justifiable homicides means that the person that shot did so justifiably, then no law was broken.True maybe more bullies and people prone to using violence will be shot because of their actions and they maybe shot by people who they consider weaker than themselves. Some would argue (not me) that their beating someone did not justify them getting shot. Most rapes do not end in justifiable homicides either, but it would not bother me if they did.

Kanuk here is the bottom line for me about guns. We are a country of very unrestricted movements and high personal freedoms. There was a time when the idea of high personal freedom was tied to high responsibility. There was also a sense of respect and responsibility for each other and our communities. Those are becoming less and less.

Frankly I do not think it will get better for two reasons. One after decades of raising children to think they are special for just being alive has produced a growing number of self-centered, narcissists who have no respect or empathy for others. Add non stop media telling everyone they should be expecting more and more for less and less coupled to increasing economic and social instability has pushed more and more towards the brink.

No amount of laws either way will fix it until we begin to take personal responsibility not only ourselves, but for our world around us. The golden rule may be sappy to some, but most people still respond to kindness, respect and love. But, there are some that do not respect anything and they are reason I will not give up my gun.
M Todd: Overall, I agree with the thrust of your comment. With regards to your first paragraph, I need to point out that even if you don’t have laws, such as the SYG or the Castle Doctrine, very few prosecutors will charge someone who was truly defending him- or herself. In Canada, you don’t have such laws and I’m certain people whose life was at play have not been charged, even less convicted if it came to that, in the event they killed an attacker (unless an illegally obtained firearm was used).