THE BASIC AREA OF IMPRECISION INVOLVES THE TERMINOLOGY OF A PERSON WITH 'DISEASE OF THE MIND' IN CONTRAST TO REFERENCE TO A PERSON 'WHOSE MIND IS DISORDERED,' THE DISORDER BEING CAUSED BY SOME EXTERNAL SOURCE. THE FORMER APPLIES TO INSANITY DEFENSES IN AUSTRALIA WHILE THE LATTER REFERS TO AUTOMATISM DEFENSES. SINCE THE BURDEN OF PROVING THE EXISTENCE OF THE CONDITION FALLS ON THE DEFENSE IN INSANITY DEFENSES, AND DISPROVING THE CONDITION OF INVOLUNTARINESS FALLS ON THE PROSECUTION IN AUTOMATISM DEFENSES, DEFENDANTS FAVOR THE LATTER. A REVIEW OF RELEVANT CASES IN QUEENSLAND, WESTERN AUSTRALIA, AND TASMANIA POINTS OUT THE DIFFICULTIES IN SORTING OUT THE NECESSARY CONDITIONS FOR THE TWO DEFENSES. HOWEVER, THESE CONCLUSIONS CAN BE DRAWN. (1) THE RELEVANT DEFENSE IS INSANITY WHERE A STATE OF AUTOMATISM IS BROUGHT ABUT BY MENTAL DISEASES SUCH AS EPILEPSY; (2) THE RELEVANT DEFENSE IS INVOLUNTARINESS WHERE A STATE OF AUTOMATISM IS BROUGHT ABOUT BY EXTERNAL VIOLENCE; (3) INVOLUNTARINESS MAY ALSO BE A RELEVANT DEFENSE WHEN SOMNAMBULISM OR HYPNOSIS IS INVOLVED, AS WELL AS IN A CASE OF FALLING ASLEEP WHILE DRIVING. IN QUEENSLAND AND WESTERN AUSTRALIA, THE ACCUSED HAS TO PROVE AUTOMATISM ON THE BALANCE OF PROBABILITIES AND CAN RECEIVE ONLY A SPECIAL VERDICT OF NOT GUILTY ON THE GROUND OF UNSOUNDNESS OF MIND, IF THE AUTOMATISM WAS BROUGHT ABOUT BY INTOXICATION FROM DRUGS OR LIQUOR WITHOUT INTENT. IN CONTRAST, THE ACCUSED DOES NOT BEAR THE ONUS OF PROOF IN TASMANIA. WHERE A STATE OF AUTOMATISM IS BROUGHT ABOUT BY INTOXICATION OR STUPEFACTION, AND THE ACCUSED HAS INTENTIONALLY CAUSED HIMSELF TO BECOME INTOXICATED, THEN HE HAS NO DEFENSE. AMBIGUITIES REMAIN FOR PLEADING INVOLUNTARINESS UNDER CONDITIONS WHERE THE INCAPACITATING CONDITION, THOUGH NOT CAUSED BY MENTAL ILLNESS, COULD NEVERTHELESS HAVE BEEN FORESEEN, AS IN TAKING ALCOHOL AGAINST MEDICAL ADVICE OR FAILING TO TAKE REGULAR MEALS WHILE ON INSULIN. COMMON LAW DENIES THE DEFENSE OF INVOLUNTARINESS UNDER SUCH CIRCUMSTANCES, WHILE IT IS STILL PERMISSIBLE UNDER THE CODES OF THE THREE AUSTRALIAN JURISDICTIONS. FOOTNOTES ARE INCLUDED. (MRK)