Criminal law in the UK: an overview of how the system works

Criminal law in England and Wales protects the public by prosecuting conduct that society has decided is so harmful that the state must respond. Unlike civil law, where disputes between individuals are settled through courts, criminal law prosecutes offences on behalf of the public, typically through the Crown Prosecution Service (CPS).

This guide explains the framework: the three categories of offence, the main statutes that define crimes, who prosecutes and defends, what defences exist, and how sentencing works.

The short version

England and Wales has a criminal justice system built on centuries of common law, now codified in key statutes. Crimes are divided into three categories based on seriousness. The police investigate, the CPS decides whether to prosecute, and the courts (magistrates' courts for less serious cases, Crown Court for serious ones) decide guilt and sentence. The defendant is presumed innocent until guilt is proven beyond reasonable doubt. A range of defences exist, from alibi to self-defence to insanity.

At a glance: offence categories

How a criminal case begins

Before a case reaches court, several things must happen:

Police investigation. The police investigate a report of crime. They interview witnesses, gather evidence, and may arrest or question a suspect. At this stage, the police cannot charge the suspect directly in most cases; they report their findings to the CPS.

CPS charging decision. The Crown Prosecution Service reviews the police evidence and decides whether there is enough evidence to charge the suspect and whether prosecution is in the public interest. This two-part test (evidential and public interest) applies to all cases.

Charge, summons, or postal requisition. If the CPS decides to prosecute:

• The suspect may be charged at the police station and released on bail or held in custody pending a first court appearance.
• Alternatively, the CPS may issue a summons (a court order requiring the defendant to attend court on a named date) or a postal requisition (a notice sent by post).
• Serious indictable offences may result in the suspect being kept in custody.

First appearance. The defendant attends court (usually magistrates' court) for a first appearance. The charge is read, the defendant is informed of their rights, and bail or custody is decided. Most defendants enter a plea at this stage or indicate how they will plead.

The three offence categories

Summary offences. These are the least serious crimes. They are tried in the magistrates' court, which has limited sentencing powers (usually up to 6 months in custody for a single offence, or 12 months for multiple offences). The magistrates hear the evidence and decide guilt. No jury is involved. Examples include common assault, battery, minor theft (under a low threshold), and disorderly conduct. Most criminal cases are summary offences.

Either-way offences. These fall between summary and indictable offences in seriousness. They can be tried in either magistrates' court or Crown Court. The CPS has the right to choose the venue, and the magistrate can also decide the case is too serious for the magistrates' court and send it to Crown Court. If tried in magistrates' court, sentencing is limited; if in Crown Court, the judge has wider powers. Either-way offences include burglary, theft of higher value, assault causing actual bodily harm, and grievous bodily harm. The defendant also has the right in some cases to insist on Crown Court trial.

Indictable offences. These are the most serious crimes. They are tried in the Crown Court before a judge and jury. Only the Crown Court can try them. Sentencing is potentially unlimited, and life sentences can be imposed for the most serious offences. Murder, rape, robbery, serious drugs trafficking, and serious fraud are indictable. A defendant accused of an indictable offence appears first in magistrates' court for a preliminary hearing, then the case is sent to Crown Court.

Main UK criminal statutes: an overview

Theft Act 1968. The principal statute covering dishonesty. It defines theft as the dishonest appropriation of property with intent to permanently deprive the owner. This Act covers shoplifting, burglary (entry with intent to steal, or theft from a building), robbery (theft using force or threat), and handling stolen goods. Sentences range from a fine to life imprisonment depending on the seriousness and value involved.

Offences Against the Person Act 1861. One of the oldest criminal statutes still in use, it defines assault, battery, and various grades of injury: assault occasioning actual bodily harm (ABH) and grievous bodily harm (GBH). Assault is putting someone in fear of immediate harm; battery is applying unlawful force. ABH requires proof that the injury interfered with health or comfort; GBH involves serious injury. Sentences range from fine to 5 years for ABH and up to 5 years for GBH.

Misuse of Drugs Act 1971. This governs possession, supply, and production of controlled drugs. Drugs are classified in Schedule 2: Class A (heroin, cocaine, ecstasy), Class B (amphetamine, cannabis), and Class C (ketamine, anabolic steroids). Possession of any class is an offence; supply and production carry much longer sentences. Class A supply can result in life imprisonment.

Road Traffic Act 1988. This statute covers driving offences: driving without a licence, driving without insurance, careless and inconsiderate driving, dangerous driving, and driving under the influence of alcohol or drugs. Sentences range from fines to community orders for lower-level offences to 14 years imprisonment for causing death by dangerous driving.

Fraud Act 2006. This addresses dishonest conduct with intent to make a gain or cause a loss. It covers fraud by false representation (claiming something untrue), fraud by failing to disclose information, and fraud by abuse of position. It was introduced to modernise the law after the Theft Act. Sentences range from fine to 10 years imprisonment.

Crown Prosecution Service role

The Crown Prosecution Service is independent of the police and is responsible for:

• Deciding whether to prosecute cases reviewed by police
• Representing the Crown in court
• Conducting prosecutions fairly and in the public interest
• Discontinuing cases if the threshold for prosecution is no longer met

The CPS applies the Full Code Test: is there sufficient evidence that a reasonable jury would find guilt beyond reasonable doubt, and is prosecution in the public interest? If either element fails, the CPS may decline to prosecute or may discontinue a case midway through.

The CPS is duty-bound to act fairly. Prosecutors must disclose evidence that might help the defence and must present the case impartially to the court.

Burden and standard of proof

Burden: In criminal law, the burden of proof rests squarely on the prosecution. The defendant is presumed innocent. The prosecution must prove guilt; the defence does not have to prove innocence.

Standard: The standard is beyond reasonable doubt. This is the highest standard of proof in law. It is not certainty, but it requires the jury (or magistrate) to be sure, so that a reasonable person would convict on the evidence. If the jury has a reasonable doubt about guilt, the defendant must be acquitted.

Common criminal defences

Alibi. The defendant was not at the place where the crime occurred. The defendant (or a witness for the defence) must place the defendant elsewhere at the material time. Alibi is not a legal defence per se but a denial of the central fact: that the defendant was present and committed the act.

Self-defence. The law permits the use of force to defend oneself, others, or property against unlawful attack. The force used must be reasonable and proportionate. A person is not obliged to retreat; they may stand their ground. Self-defence is governed by common law and section 76 of the Criminal Justice and Immigration Act 2008.

Duress. A person is forced to commit an offence under threats of death or serious injury. For duress to succeed, the threats must be imminent, the defendant must reasonably have believed the threat would be carried out, and the defendant must have had no safe way to escape. Duress is not available as a defence to murder.

Mistake. If a defendant made an honest mistake about a fact that, if true, would mean they did not commit the offence, they may have a defence. Mistake about the law is generally not a defence, but mistake about fact can be. For example, mistakenly taking someone else's property thinking it was your own may negate the dishonesty required for theft.

Insanity. At the time of the act, the defendant did not know the nature or quality of their act, or did not know it was wrong, due to a disease of the mind. This is a very high threshold and requires medical evidence. If successful, the verdict is "not guilty by reason of insanity" rather than an acquittal. The court may order hospital detention or other disposal.

Automatism. The defendant was in a state of automatism: acting without conscious control or intention. Examples include sleepwalking or a sudden medical episode such as a seizure. The defendant acted but was not aware of their actions and had no control over them. This is a complete defence but is rarely successful.

Intoxication. The law treats involuntary and voluntary intoxication differently. Involuntary intoxication (slipped a drug without consent) may be a complete defence. Voluntary intoxication is a defence only to offences requiring specific intent (such as theft), not to offences of basic intent (such as assault). Even then, the intoxication must have prevented the defendant from forming the required intent.

Consent. In some offences, the victim's consent is a defence. For example, in cases of minor assault, if the victim consented to the contact (such as in sport or medical treatment), there may be no offence. However, consent is not a defence to serious bodily harm or sexual assault.

Age of criminal responsibility

In England and Wales, the age of criminal responsibility is 10 years old. A child under 10 cannot be prosecuted for any offence, on the presumption that they are incapable of committing a crime because they lack the maturity to understand the nature of their actions or that they are wrong.

Children aged 10 to 17 can be prosecuted. However, they are treated differently from adults: they are tried in youth court (a special magistrates' court for young people) rather than adult courts. Sentencing is also different; the court must consider rehabilitation and the best interests of the child. Young offender institutions and detention and training orders are available as alternatives to adult imprisonment.

Parental liability also applies: a parent can be fined if they fail to control their child or fail to comply with a parenting order.

Sentencing principles

Sentencing Act 2020. This Act sets out the framework for sentencing in England and Wales. The court must follow the principles outlined:

• Punishment: The sentence must punish the offender proportionate to the seriousness of the offence.
• Rehabilitation: Where possible, sentencing should aim to reform and rehabilitate the offender.
• Public protection: The court must protect the public from serious harm caused by the offender.
• Reparation: The sentence should encourage the offender to make amends to the victim and the community.

Sentencing Guidelines. The Sentencing Council produces detailed guidelines for judges and magistrates. These guidelines give ranges for sentences for each offence, taking into account factors such as the offender's culpability, harm caused, previous convictions, and personal mitigation (such as guilty plea, remorse, or hardship caused by custody).

Aggravating and mitigating factors. The court considers factors that increase seriousness (aggravating factors) such as previous convictions, premeditation, or abuse of trust, and factors that reduce it (mitigating factors) such as early guilty plea, remorse, mental health difficulties, or youth.

Custodial and non-custodial sentences. The court may impose:

• Immediate custody (a prison sentence)
• Suspended sentence (a prison term that is not served unless a condition is breached)
• Community order (unpaid work, supervision, curfew, or rehabilitation activity)
• Fine
• Discharge (conditional or absolute; the offender is convicted but receives no punishment)

The court must consider whether a custodial sentence is necessary and whether a non-custodial sentence is adequate.

Disclosure: the Crown's duty

Criminal Procedure and Investigations Act 1996 (CPIA). The CPS has a duty to disclose evidence that might help the defence, even if it is not relied upon in the prosecution case. This is called disclosure.

The defence must also disclose their case: they must provide a defence statement setting out the facts they dispute and the defence they intend to raise. This allows the Crown to identify what further disclosure might be needed.

Failure to disclose can result in the case being stayed (stopped) or convictions being overturned on appeal.

Common misconceptions

"The police must release me within 24 hours." The police can hold a suspect for up to 24 hours before a charge decision (and up to 36 or 96 hours in serious cases with an extension authorised by a superintendent or magistrate). But detention doesn't automatically end at 24 hours; the suspect may be charged, bailed, or released under investigation.

"I can refuse to go to court if I get a summons." No. Ignoring a summons is a contempt of court and an additional offence. You must attend court on the date and time specified.

"A guilty plea always leads to a shorter sentence." A guilty plea does reduce sentence, and the earlier the plea, the greater the reduction (up to a third of the sentence). But other factors are considered, and a serious offence with serious harm may carry a lengthy sentence even with a guilty plea.

"The victim decides whether to press charges." No. The CPS makes the charging decision based on evidence and public interest. The victim's wishes are considered but do not determine the outcome. This is why cases are titled "R v. [Defendant]" (R for Regina, the Crown), not "[Victim] v. [Defendant]".

"The judge must follow sentencing guidelines." Judges must follow sentencing guidelines, but they can depart from them if there is a good reason (such as an unusual feature of the case). However, a departure must be reasoned and justified.

Related concepts and further reading

To understand the full picture of criminal justice in England and Wales, explore:

• How a criminal trial works in the UK
• Magistrates' courts: jurisdiction and procedure
• Crown Court trials and jury procedure
• Appeals in criminal cases
• The criminal procedure rules
• Police powers: arrest, search, and detention
• Legal aid and access to justice
• Young offenders and youth justice
• Victim support in criminal cases
• Sentencing guidelines in detail

Sources

• Crown Prosecution Service: www.cps.gov.uk (CPS Full Code Test, charging decisions, public interest)
• Sentencing Council: www.sentencingcouncil.org.uk (sentencing guidelines, offence definitions)
• UK Government: www.gov.uk (statutes, criminal justice information)
• Criminal Justice and Immigration Act 2008, section 76 (self-defence)
• Sentencing Act 2020 (sentencing principles and framework)

Written by Peter Kolomiets, founder of CaseCalm. UK criminal law content reviewed 2026-05-28.