It is governed by different biblical responsibilities. So one can't say that capital punishment is patently immoral on biblical grounds. It just isn't. There's a good reason why. It has to do with something I explained very carefully to the man who interviewed me for US New and World Report on this very issue.
Capital punishment is important.
There is nothing in the New Testament that would give us any reason to think otherwise. In fact, it presumes capital punishment in many places. I was listening a couple of years ago to KABC and talk show host Michael Jackson. He was making the point that capital punishment never works. And of course, he's thinking of it as a deterrent.