MYTH: Most studies show that more guns mean less crime

Summary:

• Researcher John Lott falsely claims that two-thirds of peer-reviewed literature shows concealed carry laws reduce crime. 
• Lott’s false claim relies on obsolete work and studies in which right-to-carry (RTC) laws are not the variables of interest.
• Most studies with a national scope published since 2005 find that RTC laws increase crime, particularly aggravated assaults. In short, more guns in public means more crime.

Lott’s Claim:

In 2012, Lott published an article in the Maryland Law Review claiming that two-thirds of peer-reviewed literature shows “right to carry laws reduce crime.”

The Facts: 

Lott’s analysis is deceptive because he excludes studies that find RTC laws increase crime and many studies he lists as pro-RTC are either deeply flawed or not about concealed carry. After correcting these mistakes, only five studies not written by Lott support his claim compared to 26 studies published before 2012 which disagree that more guns means more crime.

Lott’s original list of RTC studies in Maryland Law Review included only three studies finding RTC laws increase violent crime and 11 studies finding RTC laws have no discernible effect on violent crime (which totals 14 studies disagreeing with the claim that RTC laws decrease crime). Lott’s list excluded at least 12 academic studies published between 1995 and 2011 which found RTC laws either had no effect on crime or a negative impact, either of which contradict his claim. With the addition of these 12 studies, Lott’s original list of 14 studies disagreeing with his claim expands to 26 studies.

Lott’s list claims 21 studies, articles, and books find that RTC laws reduce crime. This list, however, is highly inflated because many of the studies are either not about RTC laws, have been disavowed by the authors, or were written by Lott using flawed methodology. Five of the 21 studies Lott lists are not primarily about RTC laws. 

The following are the five of the 21studies from Lott’s list which did not measure RTC and crime. Instead, they measured safe storage laws, private security contractors, juvenile handgun possession, abortion laws, and unmarried fertility rates: 

1. John Lott and John Whitley, “Safe-Storage Gun Laws: Accidental Deaths, Suicides, and Crime,” Journal of Law and Economics, October 2001
2. Bruce Benson and Brent Mast, “Privately Produced General Deterrence,” Journal of Law and Economics, October 2001
3. Thomas Marvell, “The Impact of Banning Juvenile Gun Possession,” Journal of Law and Economics, October 2001 
4. John Lott and John Whitley, “Abortion and Crime: Unwanted children and out-of-wedlock births,” Economic Inquiry, October 2007
5. Todd Kendall and Robert Tamura, “Unmarried Fertility, Crime, and Social Stigma,” The Journal of Law and Economics, 2010

A sixth article should also be excluded from Lott’s list of 21 supporting studies because it measures the impact of RTC laws on police deaths, not general crime or even homicides:

6. David Mustard, “The Impact of Gun Laws on Police Deaths,” Journal of Law and Economics, October 2001 (MLR)

The authors of two studies that found RTC laws reduce crime no longer support their own findings because they relied on flawed Uniform Crime Report (UCR) data. In a paper about the unreliability of county-level crime data, Michael Maltz says Lott and Mustard used flawed UCR crime statistics to reach their counter-intuitive conclusion that more guns means less crime. Maltz mentions that “counties in those states with the most coverage gaps have laws permitting the carrying of concealed weapons” and “in their current condition, county-level UCR crime statistics cannot be used for evaluating the effects of changes in policy.”

7. David Olson and Michael Maltz, “Right-to-Carry Concealed Weapon Laws and Homicide in Large U.S. Counties: The Effect on Weapon Types, Victim Characteristics, and Victim-Offender Relationships,” Journal of Law and Economics, October 2001 (MLR)

Florenz Plassmann and John Whitley’s 2003 study “Confirming More Guns, Less Crime” relies on the same flawed Lott-created county data set for his 2003 book The Bias Against Guns. Ayres and Donohue uncovered multiple errors in their data set and after correcting these errors, found no evidence that RTC laws reduced crime.

8. Florenz Plassmann and John Whitley, “Confirming More Guns, Less Crime,” Stanford Law Review, 2003 (Not Peer Reviewed)

Lott also lists a study by Thomas Marvell and Carlisle Moody as pro-RTC even though 23 of the 24 jurisdictions examined found RTC laws actually increased crime. Florida was the only jurisdiction that appeared to benefit from increased concealed carry. In a 2009 Econ Journal Watch article, Ian Ayres and John Donohue explain, “Based on the state-specific estimates they generate from this new model, Moody and Marvell conclude that RTC laws are beneficial because one state – Florida – outweighs the overall harmful effects estimated for the other 23 jurisdictions.” Ayres and Donohue argue that since 23 of the 24 jurisdictions found RTC increased crime, this study should be “taken as evidence against the more guns, less crime hypothesis.”

In 2003, Marvell and co-author Tomislav Kovandzic published their study on Florida’s concealed handgun permits and crime between 1980 and 2000. They concluded “increases in permit rate growth may actually lead to slight increases in crime.” In a subsequent version, the authors changed the conclusion to “we find no credible statistical evidence that permit rate growth (and presumably more lawful gun carrying) leads to substantial reductions in violent crime, especially homicide.” The Marvell-Kovandzic study and its subsequent revision both disproved the concept  that more guns means more crime.

9. Carlisle Moody and Thomas Marvell, “The Debate on Shall-Issue Laws,” Econ Journal Watch, September 2008 

Another publication Lott cites is the lone dissent by the late conservative criminologist James Q. Wilson during the 2004 National Research Council examination of gun laws. Out of a panel of 16 scholars, Wilson was the only scholar who believed the research showed murder rates decline after the states adopted RTC laws. Lott unfairly counts Wilson’s lone dissent as one study with the weight and status equal to the majority opinion supported by 15 scholars who disagreed with Lott’s claim that more guns means less crime.

10. James Q. Wilson, Firearms and Violence: A Critical Review, National Academies Press, 2005 

Of the remaining studies, Lott is either the sole author or coauthor on six of them; all of these studies rely on the same flawed data that Maltz warned against after walking away from his own study:

11. John Lott and David Mustard, “Crime, Deterrence, and Right-to-Carry Concealed Handguns,” Journal of Legal Studies, 1997 

12. John Lott, “The Concealed‐Handgun Debate,” Journal of Legal Studies, January 1998 

13. John Lott and John Whitley, “Measurement Error in County-Level UCR Data,” Journal of Quantitative Criminology, June 2003 

14. John Lott, More Guns, Less Crime, 2010 (3rd edition) 

15. John Lott and William Landes, “Multiple Victim Public Shootings, Bombings, and Right-to-Carry Concealed Handgun Laws: Contrasting Private and Public Law Enforcement,” The Bias Against Guns, 2003 (Not peer reviewed)

16. Stephen Bronars and John Lott, “Criminal Deterrence, Geographic Spillovers, and Right-to-Carry Concealed Handguns,” American Economic Review, May 1998 (Not Peer Reviewed)

Of the original 21 studies Lott cites, only five studies by scholars other than Lott support his conclusion:

17. William Bartley and Mark Cohen, “The Effect of Concealed Weapons Laws: An Extreme Bound Analysis,” Economic Inquiry, April 1998 

18. William Bartley, “Will Rationing Guns Reduce Crime?” Economics Letters, 1999 

19. Florenz Plassmann and T. Nicolaus Tideman, “Does the Right to Carry Concealed Handguns Deter Countable Crimes? Only a Count Analysis Can Say,” Journal of Law and Economics, October 2001 

20. Carlisle Moody, “Testing for the Effects of Concealed Weapons Laws: Specification Errors and Robustness,” Journal of Law and Economics, October 2001 

21. Eric Helland and Alexander Tabarrok, “Using Placebo Laws to Test ‘More Guns, Less Crime,’” Advances in Economic Analysis and Policy, 2004 

Lott’s review was published in 2012, but the most recent study of the remaining five was published in 2004. However, most modern studies with a national scope published since 2005 find that RTC Laws increase crime.

Lott’s counter:

Melinda Wenner Moyer, a science journalist and contributing editor at Scientific American, countered Lott’s findings in her article, “More Guns Do Not Stop More Crimes, Evidence Shows,” published in the October 1, 2017 issue of Scientific American. Moyer concludes, “when all but a few studies point in the same direction, we can feel confident that the arrow is aiming at the truth—which is, in this case, that guns do not inhibit crime and violence but instead make it worse.”

On Nov. 10, 2017, Lott posted a response on his website to Moyer’s rebuttal in Scientific American in addition to his submitted letter to Scientific American. Lott complains that Moyer used his list from the 2012 Maryland Law Review article instead of “the more complete list on our website that we provided to her.”

Lott states in his response that Moyer’s article “is very biased and ignores virtually all of the literature on right-to-carry laws and gun ownership since 1998.” He accuses Moyer of ignoring 24 peer-reviewed publications that show crime falls after people are allowed to carry concealed handguns. 

Lott also responds to criticism that RTC laws were not the focus of five of the original studies. Lott explains, “Just because a paper is generally on safe storage laws or abortion doesn’t mean that it doesn’t also account for other factors. Those papers also include a variable for right-to-carry laws. Even though I provided her with links to actual copies of the papers, it appears that Moyer did nothing more than read the titles of the papers.” Later in the post, Lott continues, “Moyers statement was that these other papers did not deal with right-to-carry laws.  You might argue that this particular paper doesn’t deal with them enough to draw any definitive conclusions, but for the abortion, safe storage, and minors papers (the three that she mentions), they and all the others that I list do deal with it.”

In response to Moyer’s criticism that one-third of the pro-RTC citations refer to Lott’s own work, Lott’s website explains, “Yes, a number of the pro-carry papers are by Dr. Lott, but he was counting all peer-reviewed papers that examined US data. And the three papers we’ve mentioned are all peer-reviewed. Many of Lott’s papers were co-authored with others.”

Rebuttal:

Lott defends his inclusion of studies about abortion, safe storage, and private security because the papers include RTC laws as controls. However, serious researchers would not look at a control variable coefficient for RTC laws and make a conclusion about the impacts of RTC laws. Lott’s abortion paper doesn’t include a table showing the impact of the RTC law but merely mentions it in a footnote.

Lott’s inclusion of Marvell’s Oct. 2001 article as evidence that RTC laws reduce crime is another example of why a control variable in a study focused on another policy should not be used to draw conclusions about concealed carry. Marvell’s paper measures the impact of juvenile handgun possession and only uses RTC as a dummy variable for part of the analysis. Marvell writes, “Analysis of the results for these three law variables is outside the scope of the paper. A rough summary is that the shall-issue laws have little discernible impact except for reducing rape.” 

In the past, Lott has tried to downplay the significance of control variable coefficients in his own research. For example, Lott’s data says rural areas are more dangerous than cities, despite FBI data showing the opposite. Lott’s model also suggests that a decrease in the population of middle-aged and elderly black women and an increase in unemployment would substantially decrease homicides. David Hemenway of Harvard points out the bizarreness of this strange result in Lott’s model: “a decrease of 1 percentage point in the percentage of the population that is black, female, and aged forty to forty-nine is associated with a 59% decrease in homicide.”

In his critical review of Lott’s Bias Against Guns, Hemenway explores many of the absurd findings in Lott’s data. For example, Lott’s analysis finds that closing the gun show loophole should reduce Indiana’s violent crime rate by 72% and auto theft rate by 102%, which would require auto-thieves to be returning previously stolen cars. The same model predicted an 83% increase in New York’s violent crime rate and a 95% increase in the robbery rate, which also didn’t happen. Hemenway concludes, “Lott’s results are just one piece of evidence that his models are misspecified, and should not be accepted as valid.”

Lott tries to have it both ways in his rebuttal. Either control variable coefficients are worth paying attention to, in which case Lott’s studies would be automatically dismissed for using poorly designed models, or they are not relevant and he shouldn’t be including them in a literature review as evidence on the impact of RTC laws. The truth is that while looking at control variable coefficients is one way to determine whether a model has major issues or not, they should not and can not be used as solid proof of anything on their own.

Another complaint in his rebuttal is that Moyer did not use Lott’s most current list of pro-RTC studies. On Nov. 29, 2020, Lott posted the following updated list on his Crime Research Prevention Center website:

Lott’s Pro-RTC Expanded List

1. John Lott, “More Guns, Less Crime: A Response to Ayres and Donohue,” SSRN, September 1999
2. Florenz Plassmann and John Lott, “More Readers of Gun Magazines, But Not More Crimes,” SSRN, July 2002 
3. John Lott, “Right-to-Carry Laws and Violent Crime Revisited: Clustering, Measurement Error, and State-by-State Break Downs,” SSRN, Feb. 2004
4. Carlisle Moody and Thomas Marvell, “The Debate on Shall Issue Laws, Continued,” Econ Journal Watch, May 2009
5. Carlisle Moody, Thomas Marvell, Paul Zimmerman, and Fasil Alemante, “The Debate on Shall-Issue Laws,” Review of Economics & Finance, 2014
6. Mark Gius, “An examination of the effects of concealed weapons laws and assault weapons bans on state-level murder rates” Applied Economics Letters, 2014
7. Carlisle Moody and Thomas Marvell, “The Impact of Right-to-Carry Laws: A Critique of the 2014 Version of Aneja, Donohue, and Zhang,” Econ Journal Watch, January 2018
8. Carlisle Moody and Thomas Marvell, “Do Right to Carry Laws Increase Violent Crime? A Comment on Donohue, Aneja, and Weber,” Econ Journal Watch, March 2019
9. Carlisle Moody, John Lott, and Thomas Marvell, “Did John Lott Provide Bad Data to the NRC? A Note on Aneja, Donohue, and Zhang,” Econ Journal Watch, January 2013
10. Carlisle Moody and Thomas Marvell, “On the Choice of Control Variables in the Crime Equation,” Oxford Bulletin of Economics and Statistics, October 2010

Lott’s Nov. 29, 2020 list also includes 18 studies he included in his 2012 Maryland Law Review article. In addition to adding more outdated academic work, Lott continues to include studies in which RTC laws are not the variables of interest. For example, Plassmann and Lott’s 2012 article did not study RTC laws but how subscriptions to Handguns Magazine impact crime. It is also worth noting that only one of the ten studies on Lott’s expanded list did not include Lott or Marvell as authors. Problems with Marvell and Lott’s data and analyses were discussed in the previous section.

The following 37 studies published between 1995 and 2018 contradict Lott’s claim that RTC laws reduce crime (36 if you exclude studies that aren’t primarily focused on RTC laws). The studies were found using Lott’s 2012 list as well as GVPedia’s Feb. 2019 concealed carry literature review.

Concealed Carry Studies Finding Increased Crime or No Effect, Pre-2012

“No effect” indicates a study found no increase or decrease in crime resulting from RTC laws. “Increase” indicates a study found RTC laws increase crime. “Lott excluded” indicates Lott excluded the study from his analysis. 

1. David McDowall, Colin Loftin, and Brian Wiersema, “Easing Concealed Firearms Laws: Effects on Homicide in Three States,” Journal of Criminal Law and Criminology, Fall 1995 – Increase, Lott Excluded
2. Jens Ludwig, “Concealed-Gun-Carrying Laws and Violent Crime: Evidence from State Panel Data,” International Review of Law and Economics, September 1998 – Increase
3. Dan Black and Daniel Nagin, “Do Right-to-Carry Laws Deter Violent Crime?” The Journal of Legal Studies, January 1998 – No Effect 
4. Hashem Dezhbakhsh and Paul Rubin, “Lives saved or lives lost? The effects of concealed-handgun laws on crime,” The American Economic Review, February 1998 – No Effect, Lott Excluded
5. Ian Ayres and John Donohue, “Review: Nondiscretionary Concealed Weapons Laws: A Case Study of Statistics, Standards of Proof, and Public Policy,” American Law and Economics Review, Fall 1999 – No Effect
6. John Donohue and Steven Levitt, “The Impact of Legalized Abortion on Crime,” Quarterly Journal of Economics, 1999 – No effect (study is not primarily about RTC laws, but is included here for completeness)
7. MV Hood and Grant Neeley, “Packin’ in the Hood?: Examining Assumptions of Concealed-Handgun Research,” Social Science Quarterly, June 2000 – No Effect
8. Mark Duggan, “More Guns, More Crime,” Journal of Political Economy, 2001 –  No Effect
9. Grant Duwe, Carlisle Moody, and Tomislav Kovandzic, “The Impact of Right-to-Carry Concealed Firearm Laws on Mass Public Shootings,” Homicide Studies, Nov. 2002 –  No Effect
10. Ian Ayres and John Donohue, “Shooting Down the ‘More Guns, Less Crime’ Hypothesis,” Stanford Law Review, 2003 – Increase
11. Ian Ayres and John Donohue, “The Latest Misfires in Support of the ‘More Guns, Less Crime’ Hypothesis,” Stanford Law Review, 2003 – Increase, Lott Excluded
12. Tomislav Kovandzic and Thomas Marvell, “Right-to-Carry Concealed Handguns and Violent Crime: Crime Control Through Gun Decontrol?” Criminology & Public Policy, 2003  –  No Effect
13. Paul Rubin and Hashem Dezhbakhsh, “The effect of concealed handgun laws on crime: beyond the dummy variables,” International Review of Law and Economics, 2003 –  No Effect
14. Lisa Hepburn, Matthew Miller, Deborah Azrael, and David Hemenway, “The effect of nondiscretionary concealed weapon carrying laws on homicide,” The Journal of Trauma, Mar. 2004 –  No Effect, Lott Excluded
15. John Donohue, “Guns, Crime, and the Impact of State Right-to-Carry Laws,” Fordham Law Review, 2004 – Increase, Lott Excluded
16. Tomislav Kovandzic, Thomas Marvell, and Lynne Vieraitis, “The Impact of ‘Shall-Issue’ Concealed Handgun Laws on Violent Crime Rates: Evidence From Panel Data for Large Urban Cities,” Homicide Studies, 2005 –  No Effect
17. Firearms and Violence: A Critical Review, National Research Council, 2005 – No Effect
18. Matthew Rosengart et al., “An evaluation of state firearm regulations and homicide and suicide death rates,”  Injury Prevention, 2005 – No Effect, Lott Excluded
19. Robert Martin Jr. and Richard Legault, “Systematic Measurement Error with StateLevel Crime Data: Evidence from the ‘More Guns, Less Crime’ Debate, Journal of Research in Crime and Delinquency, 2005 – No Effect, Lott Excluded
20. Jeff Strnad, “Should Legal Empiricists Go Bayesian?,” American Law and Economics Review, Spring 2007 – No Effect, Lott Excluded
21. James La Villa, “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, Dec. 2007 – No Effect, Lott Excluded
22. Patricia Grambsch, “Regression to the Mean, Murder Rates, and Shall-Issue Laws,” The American Statistician, Nov. 2008 – Increase, Lott Excluded
23. Benjamin French and Patrick J Heagerty, “Analysis of longitudinal data to evaluate a policy change,” Statistics in Medicine, Oct. 2008 – Increase, Lott Excluded
24. Ian Ayres and John Donohue, “More Guns, Less Crime Fails Again: The Latest Evidence from 1977 – 2006,” Econ Journal Watch, 2009 – Increase 
25. Ian Ayres and John Donohue, “Yet Another Refutation of the More Guns, Less Crime Hypothesis – With Some Help From Moody and Marvell,” Econ Journal Watch, 2009 – Increase, Lott Excluded
26. Abhay Aneja, John Donohue, and Alexandria Zhang, “The Impact of Right-to-Carry Laws and the NRC Report: Lessons for the Empirical Evaluation of Law and Policy,” American Law and Economics Review, Fall 2011  – Increase

Post-2012 Concealed Carry Studies Finding Increased Crime or No Effect

27. Abhay Aneja, John Donohue, and Alexandria Zhang, “The Impact of Right to Carry Laws and the NRC Report: The Latest Lessons for the Empirical Evaluation of Law and Policy,” Stanford Law and Economics Olin Working Paper, Sept. 2014 – Increase

28. Paul Zimmerman, “The deterrence of crime through private security efforts: Theory and evidence,” International Review of Law and Economics, 2014 – Increase

29. Dafney Lubin, “Repeal of the concealed weapons law and its impact on gun-related injuries and deaths,” The Journal of Trauma and Acute Care Surgery, 2014 – Increase

30. Marjorie McElroy and Will Wang, “Do concealed gun permits deter crime? Dynamic insights from state panel data,” Working Paper, 2014 – Increase, Not Peer Reviewed

31. Charles Phillips, et al., “Concealed Handgun Licensing and Crime in Four States,” Journal of Criminology, June 2015 –  No Effect

32. Steven Durlauf, Salvador Navarro, and David Rivers, “Model Uncertainty and the Effect of ShallIssue Right-to-Carry Laws on Crime,” European Economic Review, 2016 – Increase

33. Jeremy Carter and Michael Binder, “Firearm Violence and Effects on Concealed Gun Carrying: Large Debate and Small Effects,” Journal of Interpersonal Violence, 2016 – Increase

34. Michael Siegel, “Easiness of Legal Access to Concealed Firearm Permits and Homicide Rates in the United States,” American Journal of Public Health, 2017 – Increase

35. John Donohue, Abhay Aneja, and Kyle Weber, “Right-to-Carry Laws and Violent Crime: A Comprehensive Assessment Using Panel Data and a State-Level Synthetic Controls Analysis,” NBER Working Paper, 2017 – Increase (Not Peer Reviewed)

36. Cassandra Crifasi, Molly Merrill-Francis, Alexander McCourt, and Jon Vernick, “Association between Firearm Laws and Homicide in Urban Counties,” Journal of Urban Health, May 2018 – Increase

37. Mark Hamill, et al., “State Level Firearm Concealed-Carry Legislation and Rates of Homicide and Other Violent Crime,” Journal of the American College of Surgeons, 2018 –  No Effect

GVPedia’s list also included seven more publications listed under “other academic literature” that found RTC laws led to more crime. Comparing the above lists clearly shows that most studies do not support Lott’s claim that more concealed carry leads to less crime. Even before excluding articles with flawed data, Lott’s list of pro-RTC laws is smaller than the list finding RTC laws are associated with more crime or have no effect. 

GVPedia’s literature review identified 59 studies published between 1995 to 2018, as well as 20 other academic works. GVPedia’s review differs from Lott’s because GVPedia excludes studies that aren’t about RTC laws and books that aren’t peer reviewed. Of the 59 studies, 33 were published before or during 2005, and 26 were published after 2005. The review concluded that “The modern academic literature and investigation of causal pathways both reinforce the conclusion that RTC laws likely increase crime, or at best have no net beneficial effect.” Without controlling for quality, studies were evenly split on whether RTC Laws reduce, increase, or have no effect on crime. 

GVPedia’s analysis of RTC studies in its database of academic studies also found that most articles finding RTC decreased crime were published pre-2005 and most recent studies have found RTC increases crime.

Sources:

Melinda Moyer, “More Guns Do Not Stop More Crimes, Evidence Shows,” Scientific American, Oct. 1, 2017
John Lott, “More Guns Mean More Violent Crime–or Less? A Researcher Aims at Scientific American,” Scientific American, Nov. 10, 2017
John Lott, “UPDATE: Do Right-To-Carry Laws Reduce Violent Crime?,” Crime Prevention Research Center, Nov. 29, 2020
John Lott, “What A Balancing Test Will Show for Right-to-Carry Laws,“ Maryland Law Review, 2012
John Lott, “UPDATED: Letter In Scientific American And Rebuttal By Original Author,” Crime Prevention Research Center, Nov. 10, 2017
Devin Hughes, “GVPedia Concealed Carry Literature Review,” GVPedia, Feb. 27, 2019
Ian Ayres and John Donohue, “Yet Another Refutation of the More Guns, Less Crime Hypothesis—With Some Help From Moody and Marvell,” Econ Journal Watch, January 2009
David Hemenway, “Book Reviews. Lott JR, Jr. The Bias Against Guns,” Harvard T.H. Chan School of Public Health, 2003