What is the Peltzman effect in simple terms?

When cars have more safety features and people feel safer, they may drive more boldly, so part of the benefit of the safety features can be lost.

Does it mean safety regulation does not work?

No. Many empirical studies find that regulations such as seat belt laws reduced net deaths, and most conclude that offsetting behavior is usually only partial.

Peltzman Effect

📈 Economics By CampusDown Wiki Editorial Team Last updated October 27, 2026

The Peltzman effect is the hypothesis advanced by the University of Chicago economist Sam Peltzman in a 1975 study of automobile safety regulation that rules reducing the harm from accidents, such as mandated safety devices, lower the cost of risky driving, leading drivers to drive more aggressively and offsetting some or all of the expected safety benefit. It is also called the offsetting behavior hypothesis or risk compensation.

Contents

1. Peltzman's study
2. Risk compensation and risk homeostasis
3. The empirical debate
4. FAQ
5. References

Peltzman's study

Peltzman (1975) analyzed the effects of US automobile safety standards introduced in the 1960s, such as seat belts and energy-absorbing steering columns. He assumed that drivers rationally trade off safety against driving intensity, such as speed. Because safety devices reduce harm in a crash, they lower the expected cost of risky driving, and drivers respond by driving faster and more aggressively. He estimated that although occupant deaths fell, harm to pedestrians and cyclists rose, so total fatalities did not differ much from pre-regulation trends. Together with the economic theory of regulation of Stigler (1971) and Peltzman (1976), the study became a landmark of Chicago school regulatory research.

Risk compensation and risk homeostasis

The Peltzman effect links to the more general concept of risk compensation. Wilde (1982) proposed risk homeostasis theory, arguing that individuals adjust behavior to maintain a target level of risk, so technical safety measures alone cannot lower accident rates in the long run. Aschenbrenner and Biehl (1994) reported from a Munich taxi experiment that drivers of cars with anti-lock brakes tended to follow more closely. Viscusi (1984) reported a lulling effect in which child-resistant packaging reduced parental vigilance.

The empirical debate

Robertson (1977) sharply criticized Peltzman's data and model specification, and Crandall and Graham (1984) produced new estimates indicating that regulation reduced net fatalities. Evans (1986) concluded that traffic accident data do not support full risk homeostasis. Cohen and Einav (2003) reported that mandatory seat belt laws raised usage and reduced deaths, with weak evidence of offsetting behavior. Levitt and Porter (2001) re-estimated the effectiveness of safety devices accounting for sample selection, while Winston, Maheshri and Mannering (2006) found that offsetting could be substantial for airbags and anti-lock brakes. Hedlund (2000) set out the conditions under which offsetting occurs and concluded that it is usually partial.

FAQ

What is the Peltzman effect in simple terms?: When cars have more safety features and people feel safer, they may drive more boldly, so part of the benefit of the safety features can be lost.
Does it mean safety regulation does not work?: No. Many empirical studies find that regulations such as seat belt laws reduced net deaths, and most conclude that offsetting behavior is usually only partial.

Sources reviewed: 2026-10-26

References

Peltzman, S. (1975). The effects of automobile safety regulation. Journal of Political Economy, 83(4), 677–725.
Peltzman, S. (1976). Toward a more general theory of regulation. Journal of Law and Economics, 19(2), 211–240.
Wilde, G. J. S. (1982). The theory of risk homeostasis: Implications for safety and health. Risk Analysis, 2(4), 209–225.
Robertson, L. S. (1977). A critical analysis of Peltzman's "The effects of automobile safety regulation". Journal of Economic Issues, 11(3), 587–600.
Crandall, R. W., & Graham, J. D. (1984). Automobile safety regulation and offsetting behavior: Some new empirical estimates. American Economic Review, 74(2), 328–331.
Evans, L. (1986). Risk homeostasis theory and traffic accident data. Risk Analysis, 6(1), 81–94.
Aschenbrenner, M., & Biehl, B. (1994). Improved safety through improved technical measures? Empirical studies regarding risk compensation processes in relation to anti-lock braking systems. In R. M. Trimpop & G. J. S. Wilde (Eds.), Challenges to Accident Prevention (pp. 81–89). Groningen: Styx.
Cohen, A., & Einav, L. (2003). The effects of mandatory seat belt laws on driving behavior and traffic fatalities. Review of Economics and Statistics, 85(4), 828–843.
Levitt, S. D., & Porter, J. (2001). Sample selection in the estimation of air bag and seat belt effectiveness. Review of Economics and Statistics, 83(4), 603–615.
Hedlund, J. (2000). Risky business: Safety regulations, risk compensation, and individual behavior. Injury Prevention, 6(2), 82–89.
Viscusi, W. K. (1984). The lulling effect: The impact of child-resistant packaging on aspirin and analgesic ingestions. American Economic Review, 74(2), 324–327.
Winston, C., Maheshri, V., & Mannering, F. (2006). An exploration of the offset hypothesis using disaggregate data: The case of airbags and antilock brakes. Journal of Risk and Uncertainty, 32(2), 83–99.
Stigler, G. J. (1971). The theory of economic regulation. Bell Journal of Economics and Management Science, 2(1), 3–21.

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This article was last updated on October 27, 2026. It is based on widely recognized original works and textbooks; when citing it in a paper, please check the original sources listed in the references.