You're correct. I am a psychologist (though I don't do clinical work) and I'm generally pretty tough on criminals. I've read what's out there on her condition and I'm convinced that she was extremely mentally ill at the time. She had postpartum psychosis - which is different than postpartum depression. Years ago Charles Krauthaumer (not sure I'm spelling his name right) had an excellent editorial explaining why he thought Andrea Yates should be found not guilty by reason of insanity (this might have been during the first trial). He did a great job explaining what, as you say, is hard to explain. The best analogy I can come up with is breaking the speed limit to get a sick person to the hospital. You know that you are doing something wrong and breaking the law, but you are doing it to save a life, so it is the "right thing" to do.