Alcohol and Other Drug (‘AOD’) use is prevalent in Australia and worldwide, and is frequently a factor in many crimes. Police are often required to assess whether an individual is relevantly intoxicated. This article reviews the current laws and research surrounding intoxication detection by police, with a focus on Australia. It finds that legislation governing criminal law and police powers offers little guidance, and training in intoxication assessment appears to be underdeveloped. It concludes that assumptions of police expertise in AOD intoxication detection should be viewed with caution. Further research is required into the adequacy of initial and continuing police training, and into the practices employed by police officers on the streets, at the police station, and in the courtroom.