The purpose of traffic law enforcement is to deter risky driving behaviours. The aim of this study was to examine the individual factors of demographic, personality constructs, and attitudes for their association with perceived legitimacy of traffic law enforcement of sleep-related crashes. In total, 293 drivers completed a survey that assessed perceived legitimacy of enforcement and attitudes towards sleepy driving, as well as individual factors of demographic, personality and risk taking factors. The results demonstrate that younger drivers, drivers with higher levels of extraversion, and those with tolerant attitudes towards sleepy driving were less likely to agree that it is legitimate to charge someone if they crash due to sleepiness. The attitudes towards sleepy driving variable had the largest association with perceived legitimacy. Thus, the factors associated with perceived legitimacy of traffic law enforcement of sleep-related crashes are multifaceted. Overall, the findings have relevance with attitudinal and behaviour change programs, particularly with younger drivers.