I suppose if I had a family member killed by someone and they got off scot free on a dang technicality, I might definitely support that.
Then you would be no better than the person who killed that family member.
Dexter is little different than the guy who pulls the switch or injects the poison into a death row prisoner. They perform murder on a regular basis and even get paid handsomely for it.
It's not murder. As much as I hate the death penalty, it is a recognized part of the legal system. It IS the system. It is subject to laws, and due process. Neither of which apply to Dexter. He kills who he WANTS to kill.
With a few exceptions, Dexter goes out of his way to make sure his victims deserve what he does to them.
It's not his call to make.
Again, it's no different than the legal system.
It's very different, of course. Dexter may follow, or claim to follow, his own personal code, but that is subject to his own whims and desires. He is not beholden to a legal precedent. He is not bound by law. (The only law that matters is the law that society has put in place. His own personal desires are irrelevant. A personal code can change in a second; the law can only change when the people allow it.)
Dexter simply doesn't follow those laws.
No one gave him the right not to.
And while he's also a serial killer by definition, he doesn't target random or innocent people.
About that: 1) I don't fucking care WHO he targets. 2) He may not target innocent people NOW, but he could if he felt like it. Do you realize how dangerous that is? Never mind the damn code - Dexter simply kills
whoever he wants to. Nothing can be more dangerous to a civilized and ordered society. He may claim to target only criminals now, but one day he may decide to kill the next person he sees just because he doesn't like the way they look at him, or the hat they're wearing, or how revealing their clothes are, or anything like that. Does that sound like a society you want to live in? Where you could be his next target?
And in the end, everyone - even the most dangerous criminals who ever lived - deserves a fair trial.
Dexter will not give them one. He allows no opportunity for self defense or representation. He is simply chaos.