'Actus non facit reum, nisi mens sit rea '- 'An act does not make a person legally liable unless the mind is legally blameworthy'.

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'Actus non facit reum, nisi mens sit rea '

- 'An act does not make a person legally liable unless the mind is legally blameworthy'.

'Mens rea' or 'blameworthy mind' as one of the essential components of criminal liability is very difficult to define precisely inasmuch as 'blameworthy ' can have a different meaning dependant on the offence. The courts have developed various approaches to clarify the meaning and definition of these required elements in the common law as well as the defences that mitigate or negative mens rea to varying degrees. An act can be completed but no liability falls on the defendant if he can disprove mens rea. Liability may be mitigated partially or completely either by a recognised defence or reasonable mistake. However, there are circumstances where mens rea is found or not required and the defendant is blameless, but liability still conferred.

The maxim 'actus non facit reum, nisi mens sit rea' forms the basis for defining the 2 elements that must be proved before a person can be convicted of a crime, the actus reus or 'guilty act' and mens rea or 'blameworthy mind'. In B (a minor) v D.P.P. [2000] 2 AC 428, the appeal court held that "Mens rea was an essential element of every criminal offence unless Parliament expressly or by necessary implication provided to the contrary."

There has for centuries been presumption that Parliment did not intend to make criminals of persons who were in no way blameworthy for 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 Pmt, we must read in words appropriate to require mens rea .. 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.1 Lord Nichols in B ( a minor) v. DPP.

Definition of 'blameworthy' is quite wide and is subject to convention and interpretational precedent as laid down in case law by the judiciary. The burden of proof for the mens rea is on the prosecution. The prosecution must prove the defendant had mens rea at the time of the commission of the offence in order to secure a conviction. However, deciding the existence of defendant's mens rea is a matter for the jury.

We have no difficulty in practice making confident assertions about the mental processes in others. We rely on our inferences from observable data. The jury is a representative body of the entire community to safeguard against unfair consideration as a conviction requires unanimous agreement as to mens rea . Peter Brett2

The jury's decision is based on the evidence as perceived by them. If the defendant pleads a defence that negates the MR for the offence, the jury must decide whether they believe the D or whether his testimony is deception.

In Sweet v. Parsley [1970] A.C. 132 , Lord Pearce stated:

If the prosecution have to prove the defendant's knowledge beyond all reasonable doubt, it may be easy for the guilty to escape. But it would be very much harder for the guilty to escape if the burden of disproving mens rea or knowledge is thrown on the defendant.

Interestingly, the Australian high court has evolved a defence of reasonable mistake of fact and the burden of proving this on the balance of probabilities rests on the defendant. Professor Howard discusses the matter in an article, who concludes:

When a statutory prohibition is cast in terms, which at first sight appear to impose strict responsibility, they should be understood as merely imposing responsibility for negligence but emphasizing that the burden of rebutting negligence by affirmative proof of reasonable mistake rests upon the defendant.3

Actus reus and mens rea must coincide for criminal liability. The courts will construe acts in 2 ways; 'continuing acts' and 'one transaction' to satisfy the mens rea for an offence. In Fagan v. Metropolitan Police Commissioner 1969 1 Q.B. 439, the defendant accidentally drove his car over a policeman's foot, but refused to immediately remove the car. It was held that the actus reus was a continuing act and that refusal to move the car was sufficient as subsequent mens rea. Sometimes the courts consider a series of acts as one transaction and liability occurs if there is actus reus and mens rea at some point during the transaction. In Thabo Meli v. R (1954) 1 All ER 373, PC, the Privy Council held that this was a series of planned acts. The mens rea and actus reus had coincided during the series and therefore all the defendants were guilty of murder.

The mens rea varies from crime to crime and is either established by statute or by precedent. Some crimes require knowledge of certain circumstances the crime of receiving stolen goods requires the defendant to know that they were stolen. Some crimes require no mens rea, these are crimes of strict liability. There is a hierarchical structure of degrees of mens rea. These can be summarised as intention, recklessness, knowledge, and negligence.
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Although the mere intention to commit a misdemeanour is not criminal, some act is required to make it so.." and added "We do not think that all acts towards committing a misdemeanour are indictable. Acts remotely leading towards the commission of the offence are not to be considered as attempts to commit it but acts connected with it are.

Parke ,B. in delivering judgement in R. v Eagleton 1855 Dears 515, as quoted in R v. Robinson in 1915.4

Intention is the mens rea for many offences both as a general mens rea and a specific ...

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