[Where in the constitution does it say anything about murder being illegal? We have all sorts of laws that regulate murder in other ways, such as the death penalty, murder by self-defense, hell, in some states you can even murder someone legally for entering your property. So unless all of these regulations are unconstitutional, your argument fails.]

You are seriously going to compare death penalty or killing in self defense with murder? Death penalty was instituted by God himself as the very basis for human government to exits with its goal to protect human life against murderers with the death penalty. (Genesis 9) You are morally banckrupt and have no arguement