The Precautionary Principle is an approach to dealing with risk and uncertainty. It is already governing environmental policy decisions in Maine dealing with biodiversity, genetically modified foods and climate change. It was arguably a major factor in the decision to invade Iraq.

Unfortunately, there has been little or no public definition or discussion of the principle. State policy-makers should initiate such a discussion, because the Precautionary Principle may be simple and unobjectionable prudence in some forms, but paralyzing and impoverishing in others. Regardless of the policy implications, it should not be governing decision-making without prior discussion.

One version of the Precautionary Principle appeared in the 1992 Rio Declaration on the Environment, which was ratified by the U.S. Senate and is therefore the law of the land: “When there are threats of serious or irreversible damage, lack of full scientific certainty shall not be used as a reason for postponing cost effective measures to prevent environmental degradation.” This “better safe than sorry” weak version is unobjectionable and prudent.

A much stronger version was published in the environmentalist’s 1998 Wingspread Declaration: “When an activity raises threats of harm to human health or the environment, precautionary measures should be taken even if some cause and effect relationships are not established scientifically. In this context the proponent of the activity, rather than the public, should bear the burden the proof.” This version reverses the burden of proof, is not limited to serious or irreversible damage and omits cost effectiveness. In practice, it is extremely risk averse, technophobic, and arguably anti-capitalist. It is also clearly governing Maine environmental policy.

The endangered species listing of Atlantic salmon and the unsuccessful efforts to protect and restore them are textbook examples of the Precautionary Principle at work. Tens of millions of dollars has been spent on protection and restoration despite a lack of evidence as to the problem or its solution, all based on some questionable science and the low probability that escaped aquaculture salmon might out compete “wild” salmon and pollute the gene pool.

Continuing efforts to ban genetically modified foods and agriculture are another example. Environmentalists have effectively reversed the burden of proof. The Food and Drug Administration has found no evidence of danger to humans, but no new technology can be proven safe before it is actually implemented, and even then, to the extent that avoided risks (such as less pesticide use) are ignored, the precautionary principle becomes a prescription for paralysis and poverty.

Climate change policy offers yet another example. Maine has embarked on an effort to reduce greenhouse gas emissions despite scientific uncertainty as to how much global warming is caused by humans and fairly strong evidence that our efforts will have no effect on the climate but will seriously damage our economy.

The Precautionary Principle is already governing much environmental policy in Maine and across the nation. Whether one approves or not such a sweeping regulatory principle should be well understood and publicly debated before being implemented.

Jon Reisman teaches environmental policy at the University of Maine at Machias, which does not necessarily share his views