the issue with death penalty is that even if you have a perfect state that makes zero mistakes when applying such penalty, it can only do so in the context of a criminal offense having been committed.

but what is a criminal offense? one person's "that's a crime" is another person's "i should be free to do that"

for example, in yemen, if you are caught performing homosexual acts as a married man, you are to be stoned to death.

in principle, a capital punishment supporter should also be okay with this.

if you are one of those who has just caught yourself saying "well... i think death penalty is okay but not like that" then you have just hit my main point like a brick wall

if the decision to apply death penalty is based on one's subjective assessment of what a crime is, then that's not rational or fair

here's some homework for you - replace "death penalty" with "any penalty" and re-run my thought sequence again :)

the very act of "criminalizing" is fraught with moral issues already, so i think we should drop all death penalties until we have perfectly solved the question "what is crime?"

for further info, here's a good one (link here, clicky!)