The Rules of Criminal Law (OCR A-Level Law): Revision Notes

The Rules of Criminal Law

What is a crime?

Criminal law forms a fundamental part of the English legal system, defining conduct that is prohibited because it threatens or harms public safety, welfare, or property. Understanding what constitutes a crime and how criminal liability is established is essential for studying criminal law.

Lord Atkin provided a clear judicial definition of crime in Proprietary Articles Trade Association v Attorney-General for Canada (1931), describing it as the act prohibited with penal consequences. This definition establishes that for something to be considered a crime, two essential features must be present:

The act must be prohibited – The conduct in question must be expressly forbidden by the state. This means the state has declared through law that certain behaviour is unacceptable and must not be performed. The prohibition creates a legal boundary that citizens are expected to respect.

The act must attract penal consequences – There must be punishment attached to the prohibited conduct. The state must have established either a maximum or mandatory sentence to be imposed upon conviction. This punitive element distinguishes criminal law from other areas of law and reflects society's condemnation of the behaviour.

While crimes vary greatly in their nature and severity, from minor public order offences to serious violent crimes, all criminal offences share these two fundamental characteristics. The requirement for penal consequences means that merely declaring something wrong is insufficient – the law must provide for punishment through imprisonment, fines, community orders, or other penalties.

Sources of criminal law

Criminal law in England and Wales derives from two principal sources, each with distinct characteristics and methods of development.

Statutory crimes are created through Acts of Parliament, following the legislative process. Parliament passes legislation that defines specific criminal offences, establishes their elements, and prescribes maximum penalties. For example, the Coroners and Justice Act 2009 created new statutory offences and reformed existing ones. Statutory crimes are written down in legislation and can be found in specific Acts of Parliament. This source of law allows for clear, detailed definition of offences and enables Parliament to respond to emerging social problems or changing societal values by creating new offences or amending existing ones.

Common law crimes develop through the doctrine of judicial precedent. These offences have been established and refined over time through judicial decisions in individual cases, rather than being enacted by Parliament. The most significant example is the law of murder, which has never been codified by statute but has evolved through centuries of case law. Judges in senior courts have developed the definition, elements, and principles applicable to such offences through their judgments. Common law crimes demonstrate the flexibility of the English legal system and its ability to adapt to new circumstances, though this flexibility has also attracted criticism for potential uncertainty.

Elements of criminal liability

Criminal liability in English law is founded upon a fundamental principle established by Sir Edward Coke in the seventeenth century, expressed in the Latin maxim: actus non facit reum nisi mens sit rea. Translated, this means an act is not guilty unless the mind is also guilty. This principle recognises that criminal liability should generally require both a prohibited action and a culpable mental state.

Actus reus: the guilty act

Actus reus refers to the physical element of a crime – the prohibited conduct, circumstances, or consequences that the law forbids. It is the external, objective element of an offence. The actus reus might consist of:

• A positive act (such as striking someone in assault)
• An omission or failure to act where there is a duty to do so
• A state of affairs (such as being found drunk in a public place)
• Consequences resulting from conduct (such as death in homicide offences)

Mens rea: the guilty mind

Mens rea represents the mental element of a crime – the defendant's state of mind at the time of committing the actus reus. It is the internal, subjective element demonstrating fault or blameworthiness. Different offences require different levels of mens rea, which may include:

• Intention (direct or oblique)
• Recklessness
• Negligence
• Knowledge

Coincidence of actus reus and mens rea

For criminal liability to be established, the actus reus and mens rea must generally occur at the same time – they must coincide. It is insufficient for someone to have the required mental state at a different time from when they committed the prohibited act. This requirement ensures that defendants are only held liable when their blameworthy state of mind relates to the prohibited conduct.

When analysing any criminal offence, it is essential to identify and prove both elements separately before concluding that liability exists. The prosecution must establish both the actus reus and mens rea beyond reasonable doubt.

Removing criminal liability through defences

Even when the prosecution proves that a defendant committed both the actus reus and possessed the required mens rea, the defendant may still avoid criminal liability by successfully establishing a defence. Defences operate in different ways: some negate an element of the offence (such as the mens rea), while others provide a justification or excuse for otherwise criminal conduct.

Absence of mens rea

If the defendant did not possess the required mental element, they generally cannot be convicted. For example, in murder, the prosecution must prove that the defendant intended to kill or cause grievous bodily harm. If the killing was purely accidental, without any such intention, the defendant cannot be guilty of murder, though they might be liable for a lesser offence such as manslaughter if other elements are satisfied.

Categories of defences

Criminal defences can be classified into two broad categories:

Mental capacity defences address situations where the defendant's mental state or capacity affects their criminal responsibility:

• Insanity – where the defendant, due to a defect of reason from disease of the mind, did not know the nature and quality of their act or did not know it was wrong (established through the M'Naughten Rules)
• Automatism – where the defendant's actions were involuntary, such as a spasm, reflex action, convulsion, or acts performed while unconscious (for example, due to concussion or sleepwalking)
• Intoxication – where the defendant's voluntary or involuntary intoxication affected their ability to form the required mens rea

General defences apply more broadly across different offences:

• Self-defence – the use of reasonable force to protect oneself, others, or property from attack
• Duress by threats – where the defendant committed the offence because of threats of death or serious injury
• Duress of circumstances – where external circumstances compelled the defendant to act
• Necessity – where the defendant acted to prevent a greater evil
• Consent – where the victim gave express or implied permission for the defendant's actions

Parties involved in criminal cases

Criminal proceedings involve three key parties, which can be usefully remembered by thinking of the word trial in the shape of a triangle, representing the three-way relationship between the judge, prosecution, and defence.

The judge

In trials on indictment (serious offences tried in the Crown Court), the judge presides over proceedings and has several crucial responsibilities:

• Deciding questions of law
• Ruling on the admissibility of evidence
• Directing the jury on relevant legal principles
• Ensuring a fair trial
• Imposing sentence if the defendant is convicted

The prosecution

The prosecution team, usually from the Crown Prosecution Service (CPS), represents the state in bringing criminal charges against the defendant. Prosecutors work closely with police to:

• Assess the quality and sufficiency of evidence
• Determine what charges are appropriate
• Decide whether prosecution is in the public interest
• Present the case against the defendant in court
• Prove the defendant's guilt beyond reasonable doubt

The prosecution brings the case on behalf of the Crown, which is why criminal cases are cited as R (Regina or Rex) v [Defendant's name]. Their role is not to secure convictions at any cost, but to present the case fairly and assist the court in reaching a just verdict.

The defence

The defence team advises and represents the defendant throughout the criminal justice process. Their involvement may begin as early as the defendant's arrest and detention at the police station. Contrary to popular misconception, the defence lawyer's job is not simply to get defendants off regardless of guilt, but rather to:

• Ensure the defendant's legal rights are respected and upheld
• Help the defendant understand the proceedings and potential consequences
• Advise on whether the plea is appropriate given the facts and evidence
• Challenge the prosecution's case and evidence rigorously
• Present any defences available to the defendant
• Mitigate any sentence if the defendant is convicted

The defence plays a vital role in ensuring the fairness of criminal proceedings and protecting defendants from wrongful conviction.

Proving criminal liability

The English criminal justice system is founded on the principle that a defendant is innocent until proven guilty. This presumption of innocence affects both the burden and standard of proof required in criminal cases.

Burden of proof

The burden of proof rests firmly on the prosecution. It is the prosecution's responsibility to provide evidence proving that the defendant committed both the actus reus and possessed the required mens rea of the charged offence. The defendant does not need to prove their innocence – they are entitled to remain silent and require the prosecution to prove the case against them.

Standard of proof

Not only must the prosecution bear the burden of proof, but they must also meet a high standard of proof. The prosecution must prove the defendant's guilt beyond reasonable doubt (sometimes expressed as beyond all reasonable doubt). This means the jury or magistrates should only convict if, having considered all the evidence, they are sure of the defendant's guilt.

If the evidence leaves them with reasonable doubt about any essential element of the offence, they must acquit. This standard is deliberately high, reflecting the principle that it is better for guilty persons to go free than for innocent persons to be wrongly convicted. The criminal standard is significantly higher than the civil law standard of balance of probabilities (more likely than not), precisely because in criminal cases, the defendant's liberty – their freedom from imprisonment – is at stake.

Reverse onus

Although the general rule places the burden on the prosecution, there are exceptional circumstances where the burden is reversed, requiring the defendant to prove certain matters. This reverse onus arises in three specific contexts:

Express statutory provision – Parliament may explicitly require the defendant to prove certain defences. For example, the Homicide Act 1957, s 2(2) provides that where a defendant charged with murder relies on the defence of diminished responsibility, it is for the defendant to prove that defence. The statute expressly reverses the normal burden of proof for this particular defence.

Implied statutory provision – Some statutes implicitly place the burden on defendants. The Magistrates' Courts Act 1980, s 101 states that where a defendant relies on a defence involving an exemption, exclusion, proviso, or excuse within legislation, the burden of proving that defence falls on the defendant. Courts must interpret whether particular statutory provisions impliedly create such a reverse burden.

Common law defence of insanity – If a defendant chooses to rely on the defence of insanity, it is for the defendant to prove they satisfy the requirements of the M'Naughten Rules. This is the only common law defence where the burden falls on the defendant.

Evaluation: compatibility with human rights

The use of reverse onus provisions has attracted significant academic debate and judicial scrutiny. Critics argue that reversing the burden of proof is incompatible with the presumption of innocence protected by human rights law, particularly Article 6(2) of the European Convention on Human Rights. Requiring defendants to prove their innocence arguably undermines this fundamental right.

However, courts have held that reverse onus provisions may be justified where they pursue a legitimate aim and are proportionate to that aim. In R v Johnstone (2003), the House of Lords examined this issue in detail, establishing principles for when reverse burdens are compatible with human rights. The court recognised that some reverse burdens are necessary and reasonable, particularly in regulatory contexts where defendants may have special knowledge of facts that would be difficult for the prosecution to prove.

This remains a developing area of law, with courts carefully scrutinising reverse onus provisions to ensure they do not unjustifiably undermine the presumption of innocence.

Aims and purpose of criminal law

Criminal law serves essential functions within society, operating with clear aims and purposes that distinguish it from other areas of law.

Aims of criminal law

The primary aim of criminal law is to identify, prohibit, and prevent behaviour that is threatening, harmful, or otherwise endangering to fundamental interests in society. These interests include:

• Life and personal safety
• Property and economic interests
• Health and physical well-being
• Security and public order
• Moral welfare and social values

By defining certain conduct as criminal, the law establishes clear boundaries for acceptable behaviour and signals society's condemnation of conduct that crosses those boundaries. The criminal law thus performs both a normative function (establishing standards of behaviour) and an expressive function (communicating society's values).

Purpose of criminal law

The purpose of criminal law is the protection of society achieved through the function of punishment. When someone breaches the criminal law, the state's response is to punish the offender. This punishment serves several purposes outlined in the Criminal Justice Act 2003, s 142:

• Punishment of offenders (retribution) – ensuring offenders receive their just deserts
• Reduction of crime (deterrence) – discouraging both the offender and others from committing crimes
• Reform and rehabilitation – helping offenders change their behaviour and reintegrate into society
• Protection of the public – preventing offenders from causing further harm
• Reparation – requiring offenders to make amends to victims or the community

Theory of criminal liability: the harm principle

Understanding why and when conduct should be criminalised is a fundamental question of criminal law theory. One influential approach is the harm principle, most notably articulated by the philosopher John Stuart Mill in his work On Liberty (1859).

The harm principle

Mill argued that the only legitimate justification for the state to criminalise conduct and restrict individual liberty is to prevent harm to others. According to this principle, the law should not prohibit behaviour merely because:

• Society disapproves of it morally
• It is contrary to religious teachings
• It offends people's sensibilities
• The individual may harm themselves

Instead, criminal law should intervene only when behaviour causes or risks causing harm to other people. This principle reflects a liberal view of the relationship between the individual and the state, emphasising personal freedom while recognising the state's role in protecting citizens from harm by others.

Application and limitations

The harm principle provides a useful framework for evaluating whether particular conduct should be criminal. It suggests that victimless crimes – where all parties consent and no one is harmed – should not be prohibited. However, the principle faces several challenges:

Despite these complexities, the harm principle remains influential in debates about criminal law reform and the scope of criminalisation. It is closely connected to discussions of law and morality – whether the law should enforce moral standards or only prevent harm.

The principle challenges lawmakers to justify criminal prohibitions by reference to the harm they prevent, rather than simply moral disapproval. This theoretical foundation helps ensure that criminal law serves legitimate purposes and does not unnecessarily restrict individual freedom.

Remember!