In its simplest form, an interlock is a device, installed in a vehicle, that monitors the safety of the vehicle and its occupants, decides whether the vehicle or its occupants are in danger and warns the occupants, or influences the operation of the vehicle. The first interlocks were designed to detect alcohol intoxicated drivers. Three categories of performance interlocks can be identified: Type I interlocks sense physiological parameters of the driver (e.g. alcohol content of alveolar air) determine the driver's level of intoxication and, after comparing this level with a criterion level (e.g. the legal limit for driving), decide whether or not the vehicle should be operated.Type II interlocks measure the behaviour of the driver with cockpit-mounted equipment (e.g. eye movement monitors) or on driving-related tasks and compare this behaviour with established norms.Types III interlocks measure driving performance directly and compare the measured values with performance norms.The purpose of this paper is to review the research, conducted on driver performance interlocks over the past 50 years, specifically on Type III devices. In addition, the review looks at recent advances in intelligent vehicle technologies that could lead to the development of a Type III device. Finally, a way forward is proposed for the development of an on-board system to detect and respond to abnormal driving behavior.