This page attempts to separate the ‘detail’ of criminal laws from their key concepts. But it should be noted that the two do overlap considerably.
Burden of proof
One of the most significant differences between civil and criminal law is the burden of proof. When making a civil claim, a claimant usually only has to prove ‘on the balance of probabilities’ that the defendant acted wrongfully. However, in criminal law, as stated in Woolmington v DPP , the prosecution must prove ‘beyond reasonably doubt’ that the defendant committed the offence in question. That is, if the defendant can raise some (objective) doubt, the defendant should not be found guilty. Though in serious (indictable) crimes, it is for the jury to decide whether that doubt exists or not. Article 6(2) of the European Convention on Human Rights, as incorporated into UK law by the Human Rights Act 1998, also requires that a defendant is proved to be guilty. It is not for the defendant to prove anything.
Proof beyond reasonable doubt is a legal burden on the prosecution in all criminal cases. If ever the burden is said to be reversed, it is still for the prosecution to prove to the civil standard that the defendant committed an offence. Often, offences will reference an ‘evidential burden’. That is, it is presumed that one or more elements of an offence are present unless the defendant can show the judge some evidence to the contrary. This is known as passing the judge, and is an acceptable alternative to putting the legal burden of proof on the defendant. In R v Lambert , the House of Lords said that it was disproportionate to require a defendant to prove that he had no knowledge of his possession drugs under the Misuse of Drugs Act 1971; an evidential burden was read into the statute in place of the legal burden for such offences committed after the implementation of the Human Rights Act 1998.
Actus reus and mens rea
Traditionally, every criminal offence is said to be made up of two elements: an actus reus and a mens rea, which roughly translates to a criminal act (including its conduct, outcome and circumstances) and a guilty mind respectively. The theory behind this is that a defendant must have both elements to be punished. It is the mens rea aspect of offences which differentiates criminal law from its civil counterparts: in tort, for example, only the act of trespassing is required, there need be no intent. According to B v DPP , serious offences will have a guilty mind read into them if no mental element is specified, unless expressly overruled by Parliament.
Despite a lack of want to punish the defendant of innocent mind, Parliament, by virtue of its legislative supremacy, is entitled to create strict liability offences, which do not require a mens rea. R v Deyemi  illustrates this, where it was irrelevant whether or not the defendant thought that firearm in his possession was torch, in light of Parliament’s wish to prevent the spread of stun guns in the Firearms Act 1968.
Where a prosecution has proved that a defendant fulfilled the actus reus and mens rea requirements of an offence, the defendant may still be able to escape punishment by invoking an applicable defence. Some defences are almost universally applicable, such as duress (which is only inapplicable to cases of murder), whereas others are offence-specific, such diminished responsibility for murder. Defences may also be either partial or complete, the latter removing all criminal responsibility from the defendant.
Actus reus, mens rea and defences in practice
The terms ‘actus reus’, ‘mens rea’ and ‘defences’ are scarcely used in statutes, however they do appear in judgments. For example, in ‘possession’ of drugs in the Misuse of Drugs Act 1971 means both physical possession and a mental intention to possess. There can be a fine line between the terms, as illustrated by R v Dadson (1850), where classing an element of an offence as part of its actus reus would have negated criminal liability; though the court chose not to adopt this approach. Conversely, in sexual offences, ‘consent’ is classed as part of the actus reus to an offence, as opposed to a defence; or else every act of sexual intercourse would constitute the actus reus of rape.
The Criminal Damage Act 1971 provides a useful example to illustrate how the concepts work in practice. Section 1 reads as follows:
(1) A person who without lawful excuse destroys or damages any property belonging to another intending to destroy or damage any such property or being reckless as to whether any such property would be destroyed or damaged shall be guilty of an offence.
(2) A person who without lawful excuse destroys or damages any property, whether belonging to himself or another—
(a) intending to destroy or damage any property or being reckless as to whether any property would be destroyed or damaged; and
(b) intending by the destruction or damage to endanger the life of another or being reckless as to whether the life of another would be thereby endangered;
shall be guilty of an offence.
(3) An offence committed under this section by destroying or damaging property by fire shall be charged as arson.
This section creates two offences, one involving ‘generic’ property damage, and another almost identical offence, but for life being endangered by the act. The actus rei of the offences are highlighted in bold, the mentes reae underlined, and the incorporated offence-specific defences italicised. But there are yet more questions to ask of these offences. Firstly, for the definition of property, section 10 excludes animals and the defendant’s own property. Secondly, arson is an aggravated version of the offence punishable with a sentence up to life. Thirdly, it is unknown whether ‘by fire’ applies to the actus reus only, or whether it extends to the mens rea also.
Fourthly, damage is undefined by the statute itself. This means looking to either other statutes, or case law. At the extremes of the concept: in Morphitis v Salmon , deconstructing a barrier without damaging its parts constituted damage as the barrier’s useful purpose was impaired; in A (A Juvenile) , spitting on a police officer was not damage, but merely wipeable and trivial, and in Drake v DPP , wheel clamping was not classed as criminal damage.
Fifthly, section 5 lists the available ‘lawful excuses’. Two are provided: where a person entitled to consent to the damage did so or would have done, and where the defendant acted reasonably to protect property which he believed was in immediate need of protection. Of course, where excuses have been the subject of criticism. Smith and Hogan suggest that the former excuse would allow a defendant to blow up an oil refinery if its fumes were damaging his plants, and in Unsworth v DPP , the defendant was entitled to cut branches of a neighbour’s tree due to its blocking of light. A belief under section 5 need not be reasonable, but merely honestly held, but in R v Hunt , it was said that the damage must at least be capable of protecting property, and in R v Hill , the damage caused was said to be too remote to protect the defendant’s own property from an immediate threat of damage.
Actus reus and causation
Alongside the actus reus in section 1 above, legal causation must be proved to link the defendant’s act with the prescribed result. This is because criminal damage is a ‘result crime’, as opposed to a ‘conduct crime’ which requires proof only of a state of affairs. For example, if the defendant were to control another person’s arm to control a sledgehammer, and in turn carry out one of the actus rei above, factually, it is the other person who committed the actus reus (but not the offence, as person may be missing the required mens rea, and would have a defence). However, legal causation would not be made out for the other person; instead, it would be the defendant who caused (in law) the criminal damage.
Causation need not be direct, however. In R v Miller , a squatter was smoking in a bed, before falling asleep. Upon waking up, he noticed the cigarette he had used smouldering on the floor, but walked off. A fire quickly started and caused damage. Lord Diplock found that Miller had caused criminal damage by way of failing to take reasonable steps to mitigate a danger he had created himself, either by omission or as a continuing act.
‘Mens rea’ can include intention, recklessness, knowledge, belief, suspicion or wilfulness, but each of these terms are undefined. Criminal damage (above) is only concerned with intent and recklessness. Historically, in R v Caldwell , recklessness was said to be an objective test, however, the leading authority for recklessness is now R v G , where two boys set newspapers on fire and left them under a bin to burn out. However, the bin caught fire, spreading to a supermarket and causing £1 million in damage. The boys clearly didn’t intent the damage, but they were also said not to be reckless as recklessness requires a risk which is both unreasonable to take and which the defendant is aware of.
Section 3 of the act tests mens rea to its limit, providing an offence if a person has anything in his custody or control with the intent to use it cause, or permit another to use it to cause damage to property or endanger life. The actus reus is almost irrelevant to this crime, as any person carrying any object satisfies its criteria. It certainly doesn’t cater for a defendant changing his mind on how to use the object.
In any offence which is not one of strict liability, the formula for an offence is often written as follows:
Offence = actus reus + mens rea – defence
The prosecution must always prove the first two elements, and usually also a lack of defence when one is raised by the defendant.
Next: Causation and homicide