In an opinion piece in the New York Times Glenn Reynolds claims:
Last month, Greenleaf, Idaho, adopted Ordinance 208, calling for its citizens to own guns and keep them ready in their homes in case of emergency. …
And it may not be a bad idea. While pro-gun laws like the one in Greenleaf are mostly symbolic, to the extent that they actually make a difference, it is likely to be a positive one.
Greenleaf is following in the footsteps of Kennesaw, Ga., which in 1982 passed a mandatory gun ownership law in response to a handgun ban passed in Morton Grove, Ill. Kennesaw’s crime dropped sharply, while Morton Grove’s did not.
This is precisely backwards. Burglaries in Kennesaw did not change significantly, while Morton Grove’s burglary rate fell by 4.5 burglaries per month. (See McDowall et al Criminology v29 p541-560 (1991). Look at the graphs:


So what made Reynolds think that crime had declined in Kennesaw? McDowall et al dryly observe:
There is a curious discrepancy between the number of burglaries reported by Kennesaw’s mayor in interviews cited by Kleck (1988) and Schmidt (1987a) and the number of burglaries reported by Kennesaw’s police department to the Federal Bureau of Investigation’s police department to the Federal Bureau of Investigation’s Uniform Crime Reporting (UCR) system. The mayor claimed to Schmidt, for example, that there were 55 residential burglaries in 1981, before he law was passed. This is greater than the total number of all burglaries — residential and otherwise — reported by the police department to the UCR. Given the mayor’s spirited advocacy of the ordinance and the apparent differences in the figures he provided in separate interviews cited by Schmidt and by Kleck, we believe the UCR counts are the more accurate of the two.
Reynolds has no excuse for spreading this falsehood, since we’ve been around on this before.
Reynolds also claims
Criminals, unsurprisingly, would rather break into a house where they aren’t at risk of being shot. As David Kopel noted in a 2001 article in The Arizona Law Review, burglars report that they try to avoid homes where armed residents are likely to be present. We see this phenomenon internationally, too, with the United States having a lower proportion of “hot” burglaries — break-ins where the burglars know the home to be occupied — than countries with restrictive gun laws.
But in The Effects of Gun Prevalence on Burglary: Deterrence vs Inducement Philip Cook and Jens Ludwig found that areas in the US with higher gun ownership tended to have more burglaries, and more burglaries where the residents were home. Internationally, it’s a wash with England having a greater hot burglary rate than the US and Canada and Australia having similar rates to the US.