This study explores how the state of ‘intoxication’ from the consumption of alcohol or other drugs is treated by the criminal justice system in Australia. The authors analysed more than 500 statutory provisions which attach significance to a person’s ‘intoxication’ for a variety of purposes, and 327 appellate court decisions handed down in Australia between 2010 and 2014 in which the court considered evidence that the accused, the victim or a witness was ‘intoxicated’ at the time of the alleged offence. The study found that ‘intoxication’ has multiple purposes in the criminal law, but there is a widespread problem of under-definition. In the absence of clear definition, intoxication is often assessed on the basis of highly subjective criteria—in contexts as diverse as public order policing and assessments of victim credibility in sexual assault trials. The authors recommend that consideration be given to the standardising the definition of ‘intoxication’, consistent with society’s expectation that criminal law should mark a clear line between ‘sobriety’ and ‘intoxication’ if the latter state is to carry penal consequences.