Practical effects of Heller and McDonald
Before both decisions, the advocates of handgun prohibition predicted blood in the streets if the laws were struck down, but John Lott points out that crime rates fell in DC and Chicago after the decisions. Not that that proves causation, of course, but as he points out, had crime rates risen, that would have made for major stories with the causation simply assumed.
I remember back when the DC handgun ban was new, there was an article arguing that homicide rates were lower after it was passed (again, with causation simply assumed). Problem was that in the year after its passage homicide rates in fact went up. The authors played with the figures until they found that if you averaged the two years before and the two years after (but not three and three), you could say that the homicide rate declined, so they used that scale and got the desired result.