416. At Common Law. At different times in the history of the common law it has been supposed or presumed that a person intends the natural and probable consequences of his acts. The danger with this form of imputed intent is that it may involve convicting a defendant who is fact lacked the required intent. The point was made by Justice Dixon in Thomas v R in 1937:
The truth appears to be that a reluctance on the part of courts has repeatedly appeared to allow a prisoner to avail himself of a defence depending simply on his own state of knowledge and belief. The reluctance is due in great measure, if not entirely, to a mistrust of the tribunal of fact — the jury. Through a feeling that, if the law allows such a defence to be submitted to the jury, prisoners may too readily escape by deposing to conditions of mind and describing sources of information, matters upon which their evidence cannot be adequately tested and contradicted, judges have been misled into a failure steadily to adhere to principle. It is not difficult to understand such tendencies, but a lack of confidence in the ability of a tribunal correctly to estimate evidence of states of mind and the like can never be sufficient ground for excluding from inquiry the most fundamental element in a rational and humane criminal code.
It was repeated in Parker v R in 1963 where, speaking for the whole Court, Chief Justice Dixon disapproved an earlier House of Lords case which adopted the ‘natural and probable’ test for intent. The modern law is well illustrated by the decision of the Western Australian Full Court in Schultz v R. Schultz was charged with murder but argued that he lacked the relevant intent. He sought to adduce expert evidence that he was on the borderline of being mentally defective, but the evidence was held inadmissible .at the trial. On appeal the verdict of guilty was quashed and a retrial ordered. Chief Justice Burt (with whom the other members of the Court agreed) said:
Once it be acknowledged that there is no legal presumption that a man intends the probable consequences of his acts and that in every case the finding to be made is specifically and exclusively as to the intention of a particular person at a particular moment of time, then, as it seems to me, all facts personal to the person concerned which have bearing or which in the judgement of reasonable men may have a bearing upon the operation of his mind are relevant to that finding. Of course, facts which go no way to distinguish the person concerned from his fellows need not be made the subject of evidence because they require no proof. But such facts as do distinguish the person concerned from his fellows in a way which could, in the judgement of reasonable men , weaken an inference as to intent otherwise based upon the facts found would seem to me to be relevant to that question …
When intent is in issue the accused may call expert evidence to establish any abnormal characteristic which he may have or which he may have had at the relevant time which is not observable by and which without instruction is unlikely to be understood by the jury which affects or which at the relevant time may have affected the operation of his mind and to establish, again in general terms, what the effect was or may have been, but it is not permissible to go further and to give an opinion as to whether the effect in the particular case was or was not such as to negative a finding of intent.
Thus evidence of customary law or traditional influences on an Aboriginal defendant, being evidence of matters ‘outside the supposed experience of ordinary people’, will be admissible if it bears on the defendant’s intent in performing the act in quest ion. There is no requirement that the defendant’s intention be within the range of ‘ordinary’ states of mind, or that his belief in the existence or absence of relevant facts be ‘reasonable’. If a particular intent is required for an offence, it is sufficient that the defendant lacked that intent, even if the defendant’s state of mind is regarded as extraordinary or ‘unreasonable’. To this extent, therefore, the criminal law allows for unusual states of mind which may be the result of adherence to Aboriginal customary laws or traditions. At the level of determining intent where this is required, the common law in Australia concentrates on the defendant’s actual state of mind, rather than imputing an intention based on ‘ordinary’ or ‘objective’ standards.
417. The Queensland and Western Australian Codes. Although both the Queensland and Western Australian Codes express the requirement of ‘intention’ in very different terms than that commonly used at common law, it appears that there is no great difference in result, and in particular that the Codes do not exclude evidence of a defendant’s actual state of mind which would be admissible and could be taken into account at common law. Similarly, neither the Tasmanian Code nor the special definition of ‘malice’ in the Crimes Act 1900 (NSW) present any difficulty in this regard.
418. The Northern Territory Criminal Code 1983. A similar situation applies under the Criminal Code 1983 (NT). except in situations where ‘intoxication may be regarded for the purposes of determining whether a person is guilty or not guilty of an offence’. The legal position where intoxication may be so regarded does however present problems: these are discussed later in the, Chapter in the context of intoxication as a ‘defence’.
419. Fitness to Plead. A problem not unrelated to that of determining intent to commit an offence in the case of a traditional Aboriginal, involves the question of fitness to plead, where the defendant does not understand the nature of the proceedings. This problem is discus sed in Chapter.
Thomas v R (1937) 59 CLR 279, 309.
(1963) 111 CLR 610, 632; on appeal (1964) 111 CLR 665 (PC), but without referring to this issue.
DPP v Smith  AC 290. This aspect of Smith’s case was overruled in the UK by the Criminal Justice Act 1967 s 8. Cf R v Hyam  AC 55, 71 (Lord Hailsham LC).
 WAR 171.
id, 174. Accordingly, he held, expert evidence was admissible to help prove the special or personal factors.
id, 176, citing R v Honner  Tas SR 1.
 WAR 171, 176.
DPP v Morgan  AC 182 (genuine but unreasonable belief in consent to sexual intercourse preludes conviction for rape), followed by McEwan v R (1979) 1 A Crim R 242 (NSW Court of Criminal Appeal). cf Pappajohn v R (1980) 111 DLR (3d) 1. See generally C Howard, Criminal Law, 4th edn, Sydney, Law Book Co, 1982, 348-59; Glanville Williams, 68-106.
See also para 433. Problems may still remain as a consequence of the definition of the mental element required for a particular offence: eg DPP v Newbury  AC 500 (manslaughter by unlawful and dangerous act: no need for belief that act unlawful or dangerous). These may be dealt with to some extent by general defences, such as honest and reasonable mistake of fact.
Problems are being experienced in England with the requirement of recklessness: cf Caldwell v DPP  AC 341; Glanville Williams, ‘Intention and Recklessness Again’ (1982) 2 Legal Studies 189; D Cowley, ‘The Retreat from Morgan’  Crim L Rev 198. It is not yet clear how Australian courts will respond to these problems.
Qld, s 23; WA, s 23. See Howard, 382-95; Mamote-Kulang of Tamagot v R (1964) 111 CLR 62; Timbu Kolian v R (1968) 119 CLR 47; Kaporonovski v R (1973) 133 CLR 209.
Tas, s 13; Valiance v R (1961) 108 CLR 56, esp 82-3 (Windeyer J).
Crimes Act 1900 (NSW) s 5; Mraz v R (1955) 93 CLR 493; Howard, 39-40.
For the general rule see NT s 31 (‘intended or foreseen by him as a possible consequence of his conduct’). For the case of intoxication see s 7.
See para 436-40.
cf R v Grant  WAR 163.
See para 579-585.