This chapter focuses mainly on regular heavy use of, and dependence on, alcohol and other substances (including illicit and prescription or over-the-counter drugs). The standards for licensing do not address acute intoxication, which is subject to drink/drug driving laws (refer to Appendix 4. Drivers’ legal BAC limits) or to policies regarding random drug and alcohol testing within workplaces. However, it is possible for a long-term dependent person to be impaired due to both chronic use and recent consumption, and these risks are factors in considering the fitness to drive of such people. More information about acute intoxication and driving can be found on driver licensing authority websites.

Chronic misuse of alcohol and other substances can lead to a syndrome of dependence, characterised by several of the following features:

• tolerance, as defined by either a need for markedly increased amounts of the substance to achieve intoxication or desired effect, or a markedly diminished effect with continued use of the same amount of substance
• withdrawal, as manifested by either the characteristic withdrawal syndrome for the substance, or the same (or a closely related) substance is taken to relieve or avoid withdrawal symptoms
• the substance is often taken in larger amounts or over a longer period than was intended
• there is a persistent desire or unsuccessful efforts to cut down or control substance use
• a great deal of time is spent in activities to obtain the substance, use the substance or recover from its effects
• important social, occupational or recreational activities are given up or reduced because of substance use
• the substance use is continued despite knowledge of having a persistent or recurrent physical or psychological problem that is likely to have been caused or exacerbated by the substance (e.g. continued drinking despite recognition that an ulcer was made worse by alcohol consumption).