What you'll learn

• What counts as a crime and where criminal law comes from.
• How criminal liability is built from actus reus and mens rea.
• Who proves what in a criminal case, including reverse onus.
• The main aims, purposes and principles behind criminal law.

The big picture: what criminal law does

Criminal law is the part of law that deals with behaviour treated as a public wrong. It is not just a private dispute between two people: the state prosecutes because the conduct is seen as harmful to society.

A criminal case is normally written as R v Defendant. The R stands for Rex or Regina, meaning the King or Queen. This shows that the prosecution is brought in the name of the Crown, not technically by the victim.

Sources of criminal law

A source of law is where a legal rule comes from. Criminal law mainly comes from statute and common law.

Statute

A statute is an Act of Parliament. Many modern offences are defined in statutes.

Examples include:

• s1 Theft Act 1968 — defines theft.
• s18 Offences Against the Person Act 1861 — creates the offence of wounding or causing grievous bodily harm with intent.
• s142 Criminal Justice Act 2003 — sets out the purposes of sentencing, including punishment, deterrence, rehabilitation, public protection and reparation.

Statutes are especially important because the principle of legality requires crimes to be clearly defined by law.

Common law

Common law is judge-made law developed through decided cases. Some criminal offences and many general principles still come from case law.

For example:

• Murder is a common law offence, even though sentencing is governed by statute.
• R v Cunningham (1957) — D tore a gas meter from a wall, gas escaped and endangered V; the case established subjective recklessness: D must foresee a risk and go on to take it.
• R v Woollin (1998) — D threw his baby towards a pram and the baby died; the case explains oblique intent where death or serious injury is a virtual certainty and D appreciates that.

Human rights and interpretation

The Human Rights Act 1998 also affects criminal law because courts must, where possible, interpret legislation compatibly with Convention rights. In criminal procedure, Article 6 ECHR is especially important because it protects the right to a fair trial and the presumption of innocence.

Elements of criminal liability

To convict someone, the prosecution normally needs to prove the required elements of the offence.

The traditional phrase is actus non facit reum nisi mens sit rea, meaning “an act does not make a person guilty unless the mind is guilty.” In simpler terms: criminal liability usually needs both a guilty act and a guilty mind.

Actus reus

The actus reus may be:

• a conduct element, such as applying unlawful force;
• a circumstance element, such as property “belonging to another” in theft;
• a consequence element, such as causing injury or death;
• an omission, meaning a failure to act, but only where the law recognises a duty to act.

In R v Miller (1983), D accidentally started a fire while squatting and then failed to deal with it; the House of Lords held that creating a dangerous situation can give rise to a duty to act.

For result crimes, causation matters. R v White (1910) shows factual causation: D put poison in his mother’s drink, but she died of a heart attack before the poison worked, so he did not cause her death. R v Pagett (1983) shows legal causation: D used a pregnant woman as a shield and police returned fire, killing her; D’s conduct remained an operating and substantial cause.

Mens rea

The mens rea depends on the offence. Common forms include:

• intention — D means to bring about a result, or in rare cases sees it as virtually certain;
• recklessness — D foresees a risk and unreasonably takes it, as in R v Cunningham (1957);
• knowledge or belief — D knows or believes a particular circumstance exists;
• dishonesty — important in theft under s1 Theft Act 1968.

Some offences are strict liability offences. This means the prosecution does not need to prove mens rea for at least one element of the offence. In Sweet v Parsley (1970), D was a teacher whose farmhouse was used by tenants for cannabis; the House of Lords said courts should presume Parliament intended mens rea unless the statute clearly indicates otherwise.

Coincidence of actus reus and mens rea

The actus reus and mens rea must normally coincide, meaning they must exist at the same time.

In Fagan v Metropolitan Police Commissioner (1969), D accidentally drove onto a police officer’s foot, then deliberately refused to move. The court treated the driving onto the foot as a continuing act, so the later mens rea coincided with the continuing actus reus.

Those involved in a criminal case

The two main sides are the prosecution and the defence.

The prosecution

The prosecution brings the case against the defendant. In most serious cases, this is done by the Crown Prosecution Service, often called the CPS. The prosecution presents evidence, calls witnesses and tries to prove the offence.

The victim is usually a witness, not the legal party bringing the case.

The defence

The defence represents the defendant. The defendant is the person accused of the crime. The defence may:

• challenge the prosecution’s evidence;
• cross-examine prosecution witnesses;
• argue that an element of the offence is not proved;
• raise a defence, such as self-defence or insanity, where relevant.

Burden of proof, standard of proof and reverse onus

Burden of proof

The burden of proof asks: who has to prove the point?

There are two useful types:

• the legal burden — the duty to prove an issue to the required standard;
• the evidential burden — the duty to produce enough evidence to make an issue worth considering.

The normal rule is that the prosecution bears the legal burden.

In Woolmington v DPP (1935), D shot his wife and claimed it was accidental. The House of Lords said there is a “golden thread” running through criminal law: the prosecution must prove the defendant’s guilt.

Standard of proof

The standard of proof asks: how convincingly must it be proved?

In criminal cases, the prosecution must prove guilt beyond reasonable doubt. Modern jury directions often say the jury must be sure of guilt.

Where the defendant bears a legal burden, the standard is usually the balance of probabilities, meaning more likely than not.

Reverse onus

A reverse onus occurs where the law places a burden on the defendant rather than the prosecution. This is an exception to the normal Woolmington principle.

Reverse burdens must be treated carefully because Article 6(2) ECHR protects the presumption of innocence.

In R v Lambert (2001), involving possession of controlled drugs, the House of Lords showed that courts may read a reverse burden as only an evidential burden where needed to protect Article 6 rights. In Sheldrake v DPP (2004), involving being drunk in charge of a vehicle, the House of Lords held that some reverse legal burdens can be justified if they are reasonable and proportionate.

Aims and purposes of criminal law

Criminal law does more than list offences. It expresses what society treats as serious wrongdoing and gives the state power to respond.

Key aims include:

• punishment — imposing deserved consequences for wrongdoing;
• deterrence — discouraging D and others from offending;
• rehabilitation — helping offenders change their behaviour;
• protection of the public — preventing further harm;
• reparation — making amends to victims or the community;
• denunciation — publicly condemning serious wrongdoing.

These overlap with s142 Criminal Justice Act 2003, which identifies major purposes of sentencing.

Theories behind criminal law

A theory of criminal law explains why the law criminalises and punishes certain behaviour.

• Retribution focuses on desert: offenders should be punished because they are blameworthy.
• Utilitarian theories focus on future benefits, such as reducing crime through deterrence, rehabilitation or incapacitation.
• The harm principle suggests criminal law should mainly be used to prevent harm to others.
• Moralism argues that some conduct may be criminalised because it is seriously immoral, even if direct harm is debated.

Principles of criminal law

The principles of criminal law are the deeper ideas that help decide whether the law is fair and legitimate.

Legality

People should only be punished for conduct that was criminal at the time they acted. The law should be clear enough for people to know what is forbidden.

Fault

Criminal liability usually requires blameworthiness. This is why mens rea is so important. Strict liability offences can be controversial because they may convict without full moral fault.

Presumption of innocence

The defendant is presumed innocent unless the prosecution proves guilt. This links directly to Woolmington v DPP (1935) and Article 6 ECHR.

Proportionality

The seriousness of the offence and sentence should match the offender’s culpability and the harm caused.

Fair labelling

The name of the offence should fairly describe the wrongdoing. For example, murder carries stronger moral condemnation than manslaughter, so the distinction matters.

Balancing principle and policy

Criminal law often balances principled fairness against practical policy. For example, reverse burdens and strict liability may help enforcement, but they can put pressure on the presumption of innocence and the fault principle.

AO3: evaluating rules and theory

When evaluating criminal law, use the frameworks OCR expects for criminal law. Ask whether the law is:

• fit for purpose — does it solve the problem it targets?
• up-to-date — does it reflect modern society?
• just or unjust — does it treat people as they deserve?
• effective or ineffective — does it reduce harm and crime?
• balanced between principle and policy — does it protect society without sacrificing fairness?
• fair or unfair — especially to defendants, victims and the public;
• based on sound moral principles — does it reflect defensible ideas about blame and responsibility?

For example, strict liability may be effective for regulatory offences because it encourages high standards, but it can be criticised as unfair if a defendant is convicted despite taking reasonable care. Reverse burdens may support enforcement, but they must be justified because they interfere with the presumption of innocence.