Mens Rea in UK Law

But in a very large number of cases there is no clear indication either way. In such cases there has for centuries been a presumption that Parliament did not intend to make criminals of persons who were in no way blameworthy in what they did. That means that whenever a section is silent as to mens rea there is a presumption that, in order to give effect to the will of Parliament, we must read in words appropriate to require mens rea.

But what about the multitude of criminal enactments where the words of the Act simply make it an offence to do certain things but where everyone agrees that there cannot be a conviction without proof of mens rea in some form? But that would be putting the presumption the wrong way round: for it is firmly established by a host of authorities that mens rea is an essential ingredient of every offence unless some reason can be found for holding that that is not necessary.

In the absence of a clear indication in the Act that an offence is intended to be an absolute offence, it is necessary to go outside the Act and examine all relevant circumstances in order to establish that this must have been the intention of Parliament. I say "must have been" because it is a 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.

In the first place a stigma still attaches to any person convicted of a truly criminal offence, and the more serious or more disgraceful the offence the greater the stimga. So he would have to consider whether, in a case of this gravity, the public interest really requires that an innocent person should be prevented from proving his innocence in order that fewer guilty men may escape.

Parliament has not infrequently transferred the onus as regards mens rea to the accused, so that, once the necessary facts are proved, he must convince the jury that on balance of probabilities he is innocent of any criminal intention. I find it a little surprising that more use has not been made of this method: but one of the bad effects of the decision of this House in Woolmington's case [1935] A.C. 462 may have been to discourage its use.

But the nature of the crime, the punishment, the absence of social obloquy, the particular mischief and the field of activity in which it occurs, and the wording of the particular section and its context, may show that Parliament intended that the act should be prevented by punishment regardless of intent or knowledge.

If a man of his own volition takes a substance which causes him to cast off the restraints of reason and conscience, no wrong is done to him by holding him answerable criminally for any injury he may do while in that condition. His course of conduct in reducing himself by drugs and drink to that condition in my view supplies the evidence of mens rea, of guilty mind certainly sufficient for crimes of basic intent.