 The result of the case was the Criminal Lunatics Act 1800 ; Parliament , concerned that similar criminals could be allowed to go free , provided that somebody found " not guilty by reason of insanity " should be remanded in custody until granted a royal pardon . The 1800 Act also put limits on what crimes a defence of insanity could be used for . Prior to the Act , it could be used in any case , but the new legislation limited the defence to indictable offences . 
