For it and for a wider range of crimes prisons are far to expensive to run and a 9mm in the back of the head is cheap. Hell with another 2.8 billion+ people coming over the next 85 years a Judge Dredd future is guaranteed.
Also fuck deterence the death penalty makes it a certainty that a criminal can never commit a crime again especially with how many get out whether by parole or escape to offend again.
It is very easy NOT to commit murder, terrorism, rape, sexually assault a child, kidnapping etc. So why shouldn't we get rid of scum.