Individuals engaging in substance misuse present health and allied professions with a range of complex challenges that often reflect lifestyles of chaos and high risk-taking behaviors, fueled by high levels of impulsivity. By its very nature, substance misuse is antisocial and often takes place out of sight and often as part of the "nighttime economy." Thus, people who have substance misuse problems are difficult to reach both to understand and to help. Illicit drug taking, being both antisocial and illegal is frequently associated with other illegal activities such as dealing to others, prostitution and other acquisitive criminal behaviour. The 'membership' concepts of in-group vs out-group apply to their actions. This