Henry Miller and Gregory Conko reply:

It has been said that an economist is someone who sees something work in practice and studies whether it could possibly work in theory. Jank and Rath and Shalit have, in effect, done the opposite: In spite of compelling evidence that the precautionary principle is being applied in a way that flies in the face of scientific principles and common sense—to the widespread detriment of consumers and commerce—they try to portray it as a neutral premise on which to base risk analysis and management. All technologies have risks and benefits, both demonstrated and hypothetical, but the precautionary principle stipulates that hypothetical risks should take precedence over substantive demonstrated benefits.

They suggest further that such documents as the European Commission's communication on the precautionary principle1 will ensure “proportional,” “nondiscriminatory,” and “consistent” risk management practices that carefully weigh “potential benefits and costs” and that are “subject to review in the light of new scientific data.” While we wish this were the case, real-world application of the precautionary principle has demonstrated that the concept remains a tool of politics, not science.

Consider the example we described. In February, the German government specifically cited the precautionary principle when it banned on the commercial growth of a Bt-maize variety a single day before the Agriculture Ministry's Office for Varieties was expected to announce its approval2. The German Central Commission for Biological Safety, a scientific group advising the government on genetic engineering, announced subsequently that the government had ignored the commission's recommendation for approval and that the commission “could perceive no scientific basis for the decision”3.

As a tool of public policy, the primary shortcoming of the precautionary principle is that it incorporates neither coherent evidentiary standards nor any clear stopping points. As we argued in our original essay, it effectively frees regulators to arbitrarily require any amount and kind of testing they wish; likewise, it permits them to ignore overwhelming evidence of a product's (or a technology's) safety and to prevent its use.

Shalit also argues that “the workings of the free market do not provide a broad enough context” in which to evaluate biotechnology products. But whatever the inadequacies and pitfalls of the market, those of regulatory politics—where true accountability is even more rare and hidden, self-interested agendas are the rule—are far greater. In any case, the primary thrust of our commentary was to suggest mechanisms intended to promote science-based risk analysis. As it is currently applied, the precautionary principle does not.