i cant be bothered to read the whole thread…but here are my thoughts. i used to be a proponent of the death penalty…to the point where when martin grossman was up for his sentence i was one of the people shouting “kill the murderer”. when i told that to my charusa he set me straight, and i have been opposed ever since.
first of all, there is not a single court in the world that conducts itself according to halacha.
second of all if there were such courts (such as batei dinim which i was not referring to with the above statement) they would be following halacha b7y NOT carrying out death sentences b’zmanenu.
the majority of courts in the world accept circumstantial evidence, some more than others.
trial by one judge and no jury is vaday wrong.
trial by jury is meaningless. a jury trial is nothing more than winning an election. it is a popularity contest. if you can get the jury to like you enough, you win regardless of the culpability of your client, or lack thereof. that is NOT justice.
there is no way to GUARANTEE that the person is actually guilty seeing as circumstantial evidence is accepted and most witnesses in murder trials are bought in to build up a case, not testify to the actual murder. regardless of that according to halacha you have to have eidim, hasraah and intense drisha v’chakirah.
the world’s justice systems have in the past killed many innocent people. as long as there is another alternative, IE jail, it is wrong to sacrifice a few innocents for the guilty masses. on this point someone told me “lets kill them and let god sort it out” i said, “thats fine for god, but what about you”?
deterrent is irrelevant so i will not address it. this is not an issue of goyim vs jews, in terms of what non jewish society should allow, because death penalties in the entire world are each potential pikuach nefesh cases waiting to happen.