The negative consequences of the abolition of the death penalty on the criminal justice system are thoughtfully illustrated by Theodore Dalrymple in his Law & Liberty essay.
It was not inevitable that the abolition of the death penalty should have had this effect, if conviction for murder had indeed carried a sentence of incarceration for life. But in order for this to have been the case, society as a whole, and the governing class in particular, including intellectuals, would have had to have sufficient faith in a moral authority to impose it. The abolition itself, in my view justified per se, was — in the manner in which it was carried out — a symptom in itself of the decline in that faith. The governing class and intellectuals believed only in their own moral authority only to defy the ‘primitive’ wishes and apprehensions of the unlettered majority. They replaced the moral view of human existence by the sociological and psychological one, with all its explaining and explaining away.