Apparently, I'm not communicating well. Juries do consider other factors besides the Constitution, and they should. That doesn't make their decision unconstitutional, but it's also not a decision that is required by the Constitution. At least in my state, abuse, even if proven, does not justify homicide. Killing an abuser in his sleep is legally homicide. My point is that regardless of what the law says, abuse should be taken into account in sentencing, even if the killing does not meet the standards for justifiable homicide or for self-defense. Not all murders deserve life without parole, but some do, and it's the considerations that are neither in the Constitution nor prohibited by the Constitution that control all of these decisions.
Juries that make decisions at variance with the constitution are overruled on appeal. Apparently I am not making myself clear. As it was explained to me when I took constitutional law, the constitution is the basis for all US law and laws or judicial decisions made at variance to the constitution do not stand up on appeal. Any lawyer worth his or her fee is capable of bringing an appeal on such an obvious basis.