the relevance of the defendant's characteristics

• should the defendnat's characteristics be taken into account when deciding if the thought they needed to defend themselves?
• In r v Martin (Anthony), the psychiatric evidence showed he had some sort of condition that caused him to perceive greater danger than the average person-- however, this was deemed irrelevant to the question of whether the defendant used reasonable force. One of the reasons for this decision is that self defence is usually raised in cases of minor assault, it was decided in this case that 'it would be wholly disproportionate to encourage medical disputes in cases of that sort.'.
• in R v Cairns, it was decided that it isn't appropriate to take into account if a defendant had a psychiatric condition, such that of paranoid schizophrenia, which may have caused the defendant to have delusions that they were about to be attacked.