Basic Principles of Criminal Law Summary

As far as mistake is concerned, where the accused pleads that he acted upon a mistake of fact or law, it is crucial that the matter of related mistake is classified. In fact, it must be determined whether either the alleged mistake denies the mens rea required for the offence charged, or if the mistake relates to the facts, and if true, would enable a defence or even possibly prevent an element from establishing actus reus. Though these defences can lighten the severe nature of an offence, the principle of mens rea is still strong enough to establish an offence to be serious.

Mens rea refers to the state of mind needed by the definition of the offence charged, whether it be expressly or impliedly defined. The most typical states of mind are intention, recklessness and knowledge, which vary from different offences. Intention is where the accused has sufficient mental state to recognise his action would produce a particular consequence and has the intention to execute it. In 'Hyam v. DPP'11, Lord Hailsham declared that intention should include 'the means as well as the end'12. There is also the within this area, the distinction between foresight and intention.

In the case of 'Moloney'13, the accused and his stepfather were rather inebriated and were quibbling as to who was the quickest to load and fire a shotgun and the deceased's request, and when the accused, being the quicker of the two, fired a blank shot, he was taunted and pulled the loaded barrel's trigger and killed him. The accused's defence was that he did not intend to kill him, but merely pulled the trigger. It was held by the courts that the mens rea for murder was an intention to kill or do serious harm, and foresight of the probability of death or serious bodily harm was neither intention nor equivalent to intention.

In this way, the state of mind of intention is limited by the principle of foresight and its probability of occurring. With recklessness, two types have been established: subjective recklessness and 'Caldwell'-type recklessness. The former is where there is a conscious taking of an unjustified or unreasonable risk. The latter is when a risk is obvious and it has been recognised that there is some risk involved or there had been no thought to the possibility of there being such a risk. Both of these are relied on to indict the accused when the offence charged is deemed as being committed either intentionally or recklessly.

In regards to this state of mind, if the intention was there, but the accused behaved recklessly, it is unlikely that either type of recklessness would work as a reasonable defence. Lord Devlin14 has indicated that there are 3 degrees of knowledge: inferred knowledge from the conduct inferred from the accused's conduct and acts so intentionally; knowledge of wilful blindness, realising that a risk could exist but refrains from enquiring;; constructive knowledge, where person did not know, but should have, known about the surrounding circumstances.

This depends on whether the accused actually believes the knowledge, and obviously, if it was believed, but there was still action and recklessness/negligence, then the offence committee would be relatively serious as it would encompass recklessness and intention, showing complete disregard to the surrounding circumstance.

In conclusion, it is not completely believable that the seriousness of an offence depends on the amount of harm caused or the defendant's state of mind. Offences can still be severe, yet little harm could have inferred, such as the case of 'Brown', where the offence of assault was committed, but there was very little bodily harm. In regards to the defendant's state of mind, there appears to be a much bigger degree of seriousness.

It does not seem possible that the principles of actus reus and mens rea could work separately all the time. At times, there can be occasions where criminal liability can exist with one, but not the other. The system of offences and criminal liability often uses the two principles as a means to reclaim justice, and the more thoughtless the action or thought, the more serious the crime.

Sometimes the seriousness of an offence depending on the harm or thought is not just the theory of 'an eye for an eye' and getting revenge, but whether it was deliberate or accidental, which maybe justifies why there are many opportunities in which the conditions of actus reus and mens rea can not be fulfilled.


Ashworth, 'Principles of Criminal Law' Cross Jones & Card, 'Intro to Criminal Law'  Iller and Goodwin, 'Criminal Litigation'  Lacey, Wells and Meure, 'Reconstructing Criminal Law, texts and materials' Smith & Hogan, 'Criminal Law'