For:
-they did a harmful crime
-it makes people think before committing a crime
-the victims can rest in peace
-killers would be scared of it
-ending their life would be better thus they won't don't do it again
Against:
-Life is worth than death
-Jail is hell
-its crazy
-it won't really help cause murders still will do it
-there is more to justice the murder might not tend to do it or they still have more to the story
hope this is good XD