A formal caution is a warning given by the police to adults who admit they are guilty of an offence. (A formal caution is not to be confused with the caution made by a policeman before starting an interview with a suspect.)

Usually this is the first offence that the person has committed, and the offence is considered to be relatively minor, such as vandalism or petty theft. A caution acts as a first official warning, and its main aim is to prevent offenders re-offending. So if they offend again, they may then be given a final warning or charged with an offence, which means they will go to court. A caution will be recorded on the police database and may be considered in court if the offender is tried for another offence.

Sometimes formal cautions have conditions attached, such as attendance at drug or alcohol misuse programmes, or interventions tackling other addictions or personal problems, such as gambling or debt management courses.

Young people aged 17 years and under may receive an official reprimand instead of a caution. If the offender continues to break the law, or commits a more serious crime, they may be charged with a crime and taken to court.