There is a third category, those that are not addressed either way in the Constitution. In my state, a woman who kills an abusive husband is guilty of murder unless he posed an immediate danger to her life or safety at the time of the killing. Justifiable homicide does not apply unless he posed an immediate danger. Even if there is absolute proof of abuse: witnesses, previous police reports, medical records, and even videotape, it's still murder if she kills him in his sleep. Still, most juries would consider that very different from the case where an abusive husband hunts down and kills the wife who has left for her own safety. There is no constitutional difference as interpreted in many states, but there is still an important distinction, a mitigating factor that should weigh heavily on the scales of justice.
There is no third state; a law is either constitutional or unconstitutional. A legal verdict rendered in a proper court hearing should be based on a fair hearing of the evidence. Courts and juries get to decide cases and an allegation of abuse as justification for homicide must comply with the particular state law which must , in turn, comply with constitutional standards.