 The law in this area is often criticised because it sets a legal standard for insanity , not a medical one . In R v Quick and <unk> [ 1973 ] QB 910 , for example , the courts decided that an assault committed when the defendant was suffering from hypoglycemia due to the taking of insulin was not insane in nature , while in R v <unk> [ 1989 ] 1 WLR 287 it was held that a crime committed while the defendant was suffering from hyperglycemia did constitute insanity . As a result , the existing law allows some diabetics to be acquitted while others are declared insane , something one academic describes as " absurd " . In R v Sullivan , a man was charged with grievous bodily harm under the Offences against the Person Act 1861 after assaulting his friend during an epileptic seizure . The House of Lords ruled that Sullivan was indeed insane , and that " it does not lie within the power of the courts to alter [ the insanity test ] " . Some critics have professed " unease " at the powers of the courts to confine people found not guilty by reason of insanity in mental hospitals , arguing that discussion of mental health should be limited to the mens rea of the crime ; if the mental condition of the defendant voided the offence 's mens rea , he should be acquitted . 
