But if you allow abuses like this in the justice system, then you get people who do this to people just for the spite of it, just because they don't like them or their beliefs.
If you allow emotion into the trials, then you get prejudice, and then you have unfair trials and unfair verdicts.
Bob, right now I am looking at this with a dispassionate eye, and you are looking at it with an emotional eye. Everything in my brain is telling me that this man deserved it - hell, when I think of what he did to those kids, it's a consolation to me that he died the way he did.
However, I am overriding that thought and impulse for revenge with the thought that: yes, he was horrible, and a description of how awful he was is more than my vocabulary can produce, however, I know that it is wrong to kill someone, and that nomatter what, you must hold true to your values. Same with having sex with a drunk woman. Sure, she might be coming on to you, and only a little drunk - but she's still drunk, and if you are a good person, you will hold onto your values of not doing drunk women, and turn her down.
EDIT: And even though it's part of who we are, that doesn't make it right.