I can just add that one way to look at it is to keep in mind that the way defences operate is that you can only claim a defence if, in fact, you are found to have committed an offence. You don't need to claim self-defence if, for instance, you didn't have the mens rea to commit the assault. It's only if you have committed an offence that these affirmative defences.... If you haven't committed the offence, you're not guilty on the basis of the offence not being proved.
