I once debated a law school professor who supported the death penalty. His argument was simple. Capital punishment is like vaccination (this was before the rise of the bizarre anti-vaxxer phenomenon). As he saw it, vaccination makes a very few people ill, while preventing disease in millions of others. With capital punishment, a few innocent people are executed, but many more people are kept safe.
( I asked him whether he’d feel that sanguine about a “few mistakes” if he were innocent and on death row. But I digress.)
More to the point, there is no credible evidence that capital punishment has a deterrent effect that protects anyone. Especially in “crimes of passion”–where one angry spouse picks up that easily-available gun and offs the other, for example–the notion that the shooter indulges in a cost-benefit analysis before pulling the trigger is ludicrous.
If we really wanted to deter murder, we’d limit possession of guns.
Justice Scalia once suggested that the execution error rate was minimal, around 0.027%. As usual, his figure was a product of ideology rather than research.
Four scholars–Samuel Gross (University of Michigan Law School), Barbara O’Brien (Michigan State University College of Law), Chen Hu (American College of Radiology) and Edward H. Kennedy (University of Pennsylvania School of Medicine)–recently examined data from the Bureau of Justice Statistics and the Department of Justice in an effort to estimate the rate of false convictions among death row defendants.
After examining 7,482 cases, they estimated that 1 in 25 death row inmates are wrongly convicted. They conclude: “With an error rate at trial over 4%, it is all but certain that several of the 1,320 defendants executed were, in fact, innocent.