About | HeinOnline Law Journal Library | HeinOnline Law Journal Library | HeinOnline

151 U. Pa. L. Rev. 1003 (2002-2003)
Beyond the Precautionary Principle

handle is hein.journals/pnlr151 and id is 1017 raw text is: BEYOND THE PRECAUTIONARY PRINCIPLE

The precautionary principle has been highly influential in legal systems all
over the world. In its strongest and most distinctive forms, the principle im-
poses a burden of proof on those who create potential risks, and it requires regu-
lation of activities even if it cannot be shown that those activities are likely to
produce significant harms. Taken in this strong form, the precautionary prin-
ciple should be rejected, not because it leads in bad directions, but because it
leads in no direction at all. The principle is literally paralyzing-forbidding
inaction, stringent regulation, and everything in between. The reason is that
in the relevant cases, every step, including inaction, creates a risk to health, the
environment, or both. This point raises a further puzzle: Why is the precau-
tionary principle widely seen to offer real guidance? The answer lies in identi-
fiable cognitive mechanisms emphasized by behavioral economists. In many
cases, loss aversion plays a large role, accompanied by a false belief that nature
is benign. Sometimes the availability heuristic is at work. Probability neglect
plays a role as well. Most often, those who use the precautionary principle fall
victim to what might be called system neglect, which involves a failure to at-
tend to the systemic effects of regulation. Examples are given from numerous
areas, involving arsenic regulation, global warming and the Kyoto Protocol,
nuclear power, pharmaceutical regulation, cloning, pesticide regulation, and
genetic modification of food. The salutary moral and political goals of the pre-
cautionary principle should be promoted through other, more effective methods.
All over the world, there is increasing interest in a simple idea for
the regulation of risk: In case of doubt, follow the precautionary princi-
ple.' Avoid steps that will create a risk of harm. Until safety is estab-
Karl N. Llewellyn Distinguished Service Professor of Jurisprudence, Law School
and Department of Political Science, University of Chicago. I am grateful for valuable
comments from Peter Dorman, Leeka Kheifets, Jack Knetsch, Saul Levmore, Eric Pos-
ner, Indra Spiecker, Adrian Vermeule, Jonathan Wiener, and the participants in the
Midwest Faculty Seminar. I am also grateful to Martha Nussbaum for helpful discus-
For general discussions of the precautionary principle, see INTERPRETING THE
PRECAUTIONARY PRINCIPLE (Timothy O'Riordan & James Cameron eds., 1994);


What Is HeinOnline?

HeinOnline is a subscription-based resource containing thousands of academic and legal journals from inception; complete coverage of government documents such as U.S. Statutes at Large, U.S. Code, Federal Register, Code of Federal Regulations, U.S. Reports, and much more. Documents are image-based, fully searchable PDFs with the authority of print combined with the accessibility of a user-friendly and powerful database. For more information, request a quote or trial for your organization below.

Short-term subscription options include 24 hours, 48 hours, or 1 week to HeinOnline.

Contact us for annual subscription options:

Already a HeinOnline Subscriber?

profiles profiles most