An argument made by a patient's mother to me (who couldn't grasp what her son said his schizophrenia was about) went like this :
If I was to stand next to you at a bus stop, point out some random person across the street who was wearing red and say, "They have to die. They have to die!" you'd be wary. If I then said, "Go and stab them! Go on, now, quickly, go and stab them!" you'd probably pull out your mobile 'phone and call the police who'd want a chat about why I was making threats to kill, which they take seriously.
Presumably you'd also ignore me, rather than stabbing up some poor soul simply because I told you to.
The mother's point was that this is what her son experiences; he has auditory hallucinations both giving comment and imperative commands. Crucially, he doesn't have delusional beliefs or delusional perception (and in fact I'm unsure how robust the diagnosis of schizophrenia is since he just hears voices). She just couldn't see why it was any different hearing them as voices compared to hearing her say something he'd normally find ridiculous and discount. She felt he should be able to treat the voices just the same way he'd treat some random meaningless stranger, "who's chirping away with rubbish!"
I don't wholly agree with her, but she got me thinking. Without delusions or cognitive distortions, as a capacitated adult (passing the MCA 2005 test), is he totally responsible for all he does? She believes he is. Courts consistently have not.