The Precautionary Principle states that in the absence of scientific certainty, risk managers should err on the side of safety. The Precautionary Principle is routinely practiced by federal agencies when they are not otherwise statutorily constrained, such as by a requirement to balance benefits and costs. Indeed, it is rare when Congress has delegated the choice of risk management framework to an Executive branch agency and that agency has chosen any framework other thanks some variant of the Precautionary Principle.
A rare event is happening before our eyes. In the case of Ebola Virus Disease, federal risk managers are not relying on the Precautionary Principle. Rarer still, they are criticizing governors for relying on it.
The risk of EBV transmission is uncertain. Every person of interest belongs to one of the cells in the table below:
|Not Contagious||False Positive
Costs and benefits can be estimated objectively.
Normative benefit-cost analysis gives equal weight to each cell. Errors, whether they be false positives or false negatives, are treated the same. All other things held constant, normative benefit-cost analysis seeks to minimize the aggregate value of both types of error.
In contrast, the Precautionary Principle places a higher value on avoiding false negatives than avoiding false positives. All other things held constant, the Precautionary Principle minimizes the value of the weighted sum of errors. The amount of precaution imposed depends on the relative magnitude of these weights.
Consistent with the Precautionary Principle, federal agency risk managers usually seek to avoid false negatives. And that aptly describes what federal risk managers are now doing with respect to personal protective equipment guidance. Having learned that its previous guidance was not protective, the Centers for Disease Control now recommends much more stringent procedures to protect health care workers. The clear goal is zero risk of EVD transmission to health care workers, and zero risk is the ultimate expression of the Precautionary Principle.
In contrast, the CDC’s guidance on managing the risk of EVD transmission outside of the health care setting is not very precautionary. The only health care workers designated as “high risk” are those known to have been exposed to contaminated blood or body fluids. Where there is uncertainty about exposure, it is assumed not to have occurred. Persons designated high risk are subject to quarantine only upon confirmation that certain clinical criteria are met. Otherwise, they are subject only to direct active monitoring and limited travel restrictions.
Several states have adopted precautionary policies more consistent with what federal risk managers normally would have established. Whether they will be able to sustain these more precautionary policies is unclear, however. In the case of Kaci Hickox, a Maine judge has ruled that the State cannot impose home-based quarantine without clear and convincing evidence that doing so is “necessary to protect other individuals from the dangers of infection.” The judge has also allowed Hickox to comply with only part of CDC’s non-precautionary guidance and denied Maine authorities the administrative discretion these guidelines provide.
This makes for a truly rare event: a fairly risk-loving rather than risk averse public health policy.