 The defence of insanity has been subject to intense criticism , particularly from the Butler Committee , which noted that the rules were " based on too limited a concept of the nature of mental disorder " , highlighting " the outmoded language of the M 'Naghten Rules which gives rise to problems of interpretation " and that the rules were " based on the now obsolete belief in the pre @-@ eminent role of reason in controlling social behaviour ... [ the rules ] are not therefore a satisfactory test of criminal responsibility " . The Committee proposed reform of the law in 1975 , followed by a draft bill from the Law Commission in 1989 ; so far , these have both been ignored by successive governments . 
