Lately I have been interested in our country’s evolution of capital punishment. I spoke with my good friend Lesley O’Neill, over at UGA law school about the topic recently. This past summer, Lesley spent time with inmates on death row and she remarked on the staggering complication of these peoples lives - lost fathers, unfaithful partners, mental issues and of course, murder. I’ve always been muted about capital punishment and whether or not it serves as a useful deterrent to violent crimes but after speaking with Lesley, I had an urge to understand more - was it possilble that capital punishment served as an effective deterrent?

The following is a look at violent crimes, sentences and executions from 1930 to 2012, where data was readily available. If data was not available, I plotted a 0 (that’s not entirely accurate, but sufficient for now).

Sentences vs. Executions vs. Violent Crimes

Interestingly, violent crimes appear to grow pretty consistently and then dip back down in 1992. Sentences also seem to decrease shortly thereafter, however, executions in this timeframe appear to increase from 31 executions in 1992 to 98 executions in 1998. The chart is interactive, so if you are having trouble visualizing the executions, just click on the data series in the legend. Also, you won’t see any executions from 1969 - 1976 or so; the Supreme Court suspended capital punishment from 1972-1976, not because it was unconstitutional per se, but rather that how it was being carried out was arbitrary and unreliable, therefore unconstitutional under the Eighth Amendment’s cruel and unusual punishment ban. Lesley was kind enough to comment on this period: “By 1976 States had re-written their death penalty statutes, which is when the Court revisited the issue and deemed that the new schemes fixed the arbitrariness and unreliability, and therefore were no longer unconstitutional. Of course, that’s very debatable as it’s carried out today.”

Lesley went on to add that it would probably be nearly impossible to prove a correlation between any drop in violent crime and the death penatly acting as a deterrent, since it is no longer reserved for the “worst of the worst” but much more so based on where the defendant is from. For example - take the Colorado shooter getting a life sentence, and then someone who shot and killed one person in Georgia or Louisiana who then gets sentenced to death (Lesley has worked on multiple cases where it was a “heat of passion” type crime involving just one or two victims). Another example is Caddo Parish in Louisiana; it is among 2% of U.S. counties responsible for 56% of all the inmates on death row. From 2010 to 2014 more people were sentenced to death per capita there than any other county in the U.S.

Of course, we have more meta information that could make this information more useful. This includes population growth, sentences, executions and violent crimes by state (which could be interesting based on where capital punishment is legal), as well as type of violent crime. We also have meta information on the method of execution from hanging, to firing squad to gas chamber (all earlier methods, naturally). If this is of interest, I’d be happy to take a deeper look. I’d also be interested in understanding what people make of these trends (if you folks are clamoring for a regression, we can talk). Comments, as always are welcome.