A 2012 report by the National Research Council of the National Academies concluded that studies claiming a deterrent effect, brutalization effect, or no effect on murder rates from the death penalty are fundamentally flawed. Criminologist Daniel Nagin of Carnegie Mellon said: "Nothing is known about how potential murderers actually perceive their risk of punishment." The report concluded: “The committee concludes that research to date on the effect of capital punishment on homicide is not informative about whether capital punishment decreases, increases, or has no effect on homicide rates".
