The law generally requires that the accused possess a ‘blameworthy’ state of mind at the time the act comprising the offence was committed, and the basic presumption is that mens rea is required for every offence (‘actus non fit reus nisi mens sit rea’), authority for which stems from Sherras v De Rutzen  –
“There is a presumption that mens rea … is an essential ingredient in every offence; but that presumption is liable to be displaced either by the words of the statute creating the offence or by the subject matter with which it deals, and both must be considered.”
This proposition, that mens rea is the default position for an offence unless its implication is clearly outweighed by other factors, was secured in Sweet v Parsley . Per Lord Reid: “it is universal principle that if a penal provision is reasonably capable of two interpretations, that interpretation which is most favourable to the accused must be adopted.” Thus the requirement of intention is presumed where a matter is uncertain.
However, many statutes do not use the language of ‘knowingly’ or ‘intentionally’ acting; in the case of such strict liability offences, usually regulatory offences without the “disgrace of criminality”, there is no element of intent whatsoever for the prosecution to establish.
Normally, an objective view of mens rea, where the defendant fails to recognise the risk of his acts where a reasonable person would have done so, (recklessness in the Caldwell sense) cannot be said to constitute intention. Rather, a subjective, purposive view of intent encompasses the intention to act or to cause a consequence, or foresight or awareness of a risk of acting or causing the consequence (Cunningham ).
For the majority of offences, recklessness will suffice for a conviction, but some do require proof of an intent, including murder (an intent to kill or inflict grievous bodily harm), theft, burglary, and wounding with intent. For the distinction between murder and manslaughter, then, the law uses intention as its main method; thus the crime and therefore the sentence can differ considerably depending on the presence or absence of intention.
There has been much controversy as to the proper meaning of intention in English criminal law. Some, including Sir John Salmond and Dr JWC Turner, believed that a result is intended only when it is desired. Conversely, it is sometimes maintained that an ‘intended’ result is not necessarily desired “directly” but merely one foreseen by the defendant as an “oblique” or probable result of his actions.
Antony Duff considered that one feature of intention is that a defendant who intends to kill another would regard himself as somehow having “failed” if that person did not die, no matter how remote the likelihood of “success”; on the other hand, if he does not intend a death, he will not think he has failed if the person survives. Thus the defendant’s true ‘purpose’ in acting may be more easily discovered. In Steane , the defendant had been compelled, through concern for the sake of his family, to make broadcasts for the enemy during the Second World War, and was prosecuted for doing an act likely to assist the enemy “with intent to assist the enemy”.
His conviction was quashed, however, in holding that although he did intend to make the broadcasts, he did so under duress: his ulterior intent had been to protect his family. In this sense, in Cunliffe v Goodman , Lord Asquith stated that the ‘core’ sense of intention “connotes a state of affairs which the party ‘intending’ … does more than merely contemplate: it connotes a state of affairs which, on the contrary, he decides, so far as in him lies, to bring about”.
In Smith , the House of Lords upheld an objective test of mens rea in murder, holding that a person is guilty where a reasonable person would have seen death as the natural and probable consequence of their actions, and simply presumed that Mr. Smith intended whatever he foresaw. Further, in Hardy v Motor Insurers’ Bureau , it was said of the accused that “he must have foreseen, when he did the act, that it would in all probability injure the other person. Therefore he had the intent to injure the other person.”
However, somewhat more recent cases accept the distinction between intention and mere foresight. The question was raised in Hyam , where the accused sought to frighten her husband’s mistress to leave the area, while realising that serious harm was a probability. It was held that, although she was reckless, she did not intend to kill. In Moloney , the House held that an intent to cause serious bodily harm is sufficient mens rea for murder, while Lord Bridge appeared to suggest that the law should regard “morally certain” consequences as intended.
Lord Scarman’s remarks in Hancock and Shankland  held that “foresight does not necessarily imply the existence of intention”. Although the defendants recognised the dangerousness of their actions, they claimed they meant only to frighten their victim, not to harm anyone. Per Lord Scarman:
“The greater the probability of a consequence the more likely it is that the consequence was foreseen and… if that consequence was foreseen the greater the probability is that that consequence was also intended… The probability, however high, of a consequence is only a factor.”
Lord Lane in Nedrick (1986) believed that a defendant might intend a result albeit not desiring it, and said that juries must consider (i) how probable the consequence was and (ii) if the defendant foresaw that consequence. He reasoned thus: that if the defendant did not foresee the consequence, it cannot be said that he intended it. If he did foresee it but thought the risk slight, the jury might easily infer that he did not intend it. If he foresaw death as virtually certain, this is a matter of factual evidence from which the jury may infer that the defendant intended that death.
Section 8 of the Criminal Justice Act 1988 supported these more recent decisions:
“A court or jury… shall not be bound to infer that he intended or foresaw a result… by reason only of its being the natural or probable consequence… but… shall decide whether he did intend or foresee that result by reference to all the evidence…”
This suggests that a jury must decide as a fact whether the defendant possessed the necessary intent, but that they may use evidence that a reasonable person would have intended the result as a guide.
Woollin  approved Nedrick, but simplified its meaning to say that a jury are not entitled to find the necessary intent unless (i) the consequence was a ‘virtual certainty’ and (ii) D appreciated that this was the case.
However, under the continuing doctrine of transferred malice, established in Latimer , where the defendant does an actus reus with the required mens rea, he is guilty of an offence even if the result is in some respects an unintended one. However, this does not operate when the divergence between actus reus and mens rea is relevant to the definition of the offence: the two must refer to the same crime (Pembliton ).
As Glanville Williams once pointed out, “the act constituting a crime may in some circumstances be objectively innocent, and take its criminal colouring entirely from the intent with which it is done”. Thus, in the case of Court , it was the defendant’s intention in spanking a young girl that made his assault on her indecent; he acted not to administer discipline but rather for sexual gratification.