We would likely see a deterrent effect if police were given martial powers to execute, on the spot, any person arrested for murder. Unlike the unproven deterrent effect, we know for a fact that in the past 25 years, over 75 innocent people sentenced to death have been subsequently freed. It took an average of six years to prove their innocence. We also know that during that same time 25 innocent people were killed by execution. We know that the death penalty is not consistently applied.
Race continues to be a factor in executions.
Not all calculated and knowing decisions that result in the taking of human lives are even prosecuted. We know that executives who make conscious economic decisions to release unsafe products that will assuredly result in the preventable deaths of innocent persons are rarely even prosecuted, and they are never executed. There cannot be swift and consistent application of the death penalty, there cannot be any deterrent effect, unless we are willing to accept the killing of innocent people. We are sometimes told that life imprisonment is unfair to taxpayers, that it is more costly than the death penalty. In the two largest death penalty states, Texas and Florida, it costs approximately six times as much to execute a person than to confine them for the rest of their lives.