The word Criminal can conjure images of murderers and robbers but anyone who breaks the law is a criminal, from tax cheats to burglars. The study of crime and the way society reacts to it is called Criminology. It is very different from a discipline that deals with the law itself, which is called Criminal Justice.

A criminal offence is an act that has been deemed to be against the public order by the authorities and is therefore punishable under the law. The types of offences and the penalties have evolved with changing societal needs and can range from the use of watchmen to incarceration.

People accused of offences have the right to legal arguments to defend them such as self-defense, mental illness and poverty. These can be heard in criminal trials where police, prosecutors and defence attorneys present evidence, question witnesses and cross-examine them. A judge or jury decides guilt or innocence. Those found guilty are punished with sentences that take into account mitigating and aggravating factors as well as the severity of the offence. These can include imprisonment in prison, a monetary fine or community service. Felonies are the most serious crimes and can be punishable by life in prison or death. Misdemeanors and infractions are less serious crimes.

Magistrates (known as Justices of the Peace in England and Wales) are part of the judiciary and hear around 85 per cent of criminal cases in the lower courts. They are appointed by the Lady Chief Justice or Lord Chancellor.