Laws of Fear: Beyond the Precautionary Principle

Posted: 11 May 2005

See all articles by Cass R. Sunstein

Cass R. Sunstein

Harvard Law School; Harvard University - Harvard Kennedy School (HKS)


What is the relationship among fear, danger, and the law? There are serious problems with the increasingly influential Precautionary Principle - the idea that regulators should take steps to protect against potential harms, even if causal chains are uncertain and even if we do not know that harms are likely to come to fruition. An investigation of such problems as global warming, terrorism, DDT, and genetic engineering shows that the Precautionary Principle is incoherent. Risks exist on all sides of social situations, and precautionary steps create dangers of their own. The idea of precaution seems operational only because diverse cultures focus on very different risks, with social influences and peer pressures accentuating some fears and reduce others. Cascades, the availability heuristic, loss aversion, and group polarization are highly relevant here. Instead of adopting the Precautionary Principle, regulators should take three steps: they should adopt a narrow Anti-Catastrophe Principle, designed for the most serious risks; pay close attention to costs and benefits; and accept an approach called "libertarian paternalism," designed to respect freedom of choice while also moving people in directions that will make their lives go better. An understanding of the dynamics of fear also shows how free societies can protect liberty amidst fears about terrorism and national security.

Keywords: precautionary principle

Suggested Citation

Sunstein, Cass R., Laws of Fear: Beyond the Precautionary Principle. Available at SSRN:

Cass R. Sunstein (Contact Author)

Harvard Law School ( email )

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Harvard University - Harvard Kennedy School (HKS) ( email )

79 John F. Kennedy Street
Cambridge, MA 02138
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