Influencing discretionary driver behaviours in Australia relies very much on the coercive strategy of deterrence. This paper stems from a thorough review of deterrence theory and risk taking carried out in 2002-03 for the Land Transport Safety Authority, New Zealand (Elliott, 2003). The paper begins by exploring the definition of deterrence leading to the proposition that if motorists do not refrain from offending out of fear of consequences they are by definition not deterred. It explores the various roles deterrence plays in influencing behaviour including its moral educative role. It argues that 'general' and 'specific' deterrence are not different mechanisms, but the same mechanism applied to different populations. The targets for 'general' deterrence are not the general population of motorists. It is limited to the marginal group of offenders or prospective offenders who can be influenced through fear, ie are likely to offend and likely to be deterred by the threat of punishment.