In 1843 one man would set a legal precedent that still utilized today in some countries.  Daniel M'Naghten would attempt to assassinate the Prime Minister of England only to be caught up in a case of mistaken identity.  Did his delusions cause his actions or was he legally sane at the time of the crime?  Listen to the story of how Daniel's actions set the standard for generations to come. The burden of proof of one's mental status is the defendant's responsibility to prove.