There is ongoing study of the extent to which individuals respond to safety-enhanced technology or environmental changes of which they are aware. Some drivers may compensate for, and thus offset, the safety gains of an improved or safety-enhanced product by reducing precautions or taking greater risks. For example, improved braking or handling can lead to increased speeds, closer following, and faster cornering (Evans, 1991). However, when the risk of injury is reduced in ways not apparent to the user, which is the case with most forms of automatic or passive protection, behavioral adaptation is unlikely to occur (Lund and O'Neill, 1986; Evans, 1991).
The proper scope of mandatory or compulsory requirements for self-protection has long been an issue in the ethical literature on paternalism and public health (Cole, 1995). No one questions the legitimacy of informing people about the benefits of wearing safety belts or motorcycle and bicycle helmets, taking steps to persuade people to wear them, or using incentives to encourage safe behavior. However, it has proved difficult in many cases to change driver behavior through educational or persuasive techniques alone. Laws, such as those requiring safety belt use and wearing of helmets, have been successful, particularly when augmented by highly publicized enforcement programs and focused educational programs (Williams et al., 1996; Lacey et al., 1997).
In recent years an important shift in public attitudes appears to have occurred, increasing the level of support for mandatory safety belt laws. The residual debate concerns the benefits and costs of increasing the level of enforcement. To what extent, and at what cost, would allowing primary enforcement2 increase the level of compliance and reduce injuries? Evidence indicates that, for a given level of enforcement, primary belt-use laws result in higher rates of usage (Campbell, 1988; NHTSA, 1995; Ulmer et al., 1995). Thus, states with secondary laws are not realizing the benefits that could be gained for the enforcement they are already supporting. Even so, there is concern among minorities that primary, or standard, enforcement could lead to police harassment. Additionally, mandatory motorcycle helmet laws remain controversial, although the evidence of effectiveness in preventing death and brain injury is well documented (Kraus et al., 1994; Kraus and Peek, 1995).