Known Unknowns: Unmeasurable Hazards and the Limits of Risk Regulation

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Oklahoma Law Review

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Known unknowns are identifiable hazards that pose an unquantifiable risk of harm. The inability to characterize known unknowns in terms of measurable risk poses a dilemma for regulators. When known unknowns cause harm, public pressure often leads Congress to mandate that agencies establish specific, science-based thresholds for acceptable risk. In response, regulators, who lack scientific evidence to justify such rules, face a choice: they can either delay the rulemaking process or fabricate a scientific justification. If they adopt the first option, they expose themselves to potential litigation by public interest groups demanding that they comply with the law. If they adopt the second option, they expose themselves to potential litigation by regulated entities challenging the new rules as arbitrary and capricious. What's an agency to do?

This Article develops general principles for addressing known unknowns using a case study of efforts to regulate agricultural water quality. Contaminated water used to cultivate fresh produce is a well-known cause of recurrent foodborne illness outbreaks. Unfortunately, it has, so far, proven impossible to reliably quantify the risk of human illness from any given source of agricultural water. A detailed analysis of the challenges that have frustrated successful regulation of agricultural water quality provides the basis for specific, feasible recommendations to help regulators cope with known unknowns in a variety of contexts, such as climate change, environmental toxins, and pandemic response.

When confronting known unknowns, regulators should prioritize harm reduction strategies that generate new policy-relevant information. Additionally, they should rely on localized private governance efforts endorsed by a broad representation of stakeholders. Finally, regulators should be more transparent about the limits of risk regulation.

Recommended Citation

Timothy D. Lytton, Known Unknowns: Unmeasurable Hazards and the Limits of Risk Regulation, 76 Okla. L. Rev. 857 (2024)



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