Important Concepts in Environmental Law--The "Precautionary Principle".

• Author: Surtees, Jeff
• Position: Columns | Environmental Law

Last issue we talked about sustainable development. This time the topic is the precautionary principle.

Most human activity has risk. When we are deciding whether we should do something, we balance the risks against the possible rewards. Risk has two parts. First, there is the probability that something bad will happen. Second, there is the seriousness or severity of that result. The two parts have to be considered together. A fifty percent probability that we will break a fingernail while fixing a light switch might be acceptable. A one percent chance that we will burn down the house doing the same task when we don't know how probably isn't.

Risk can also be external. If harm occurs, it will be to someone else or to society as a whole. Without the protection of regulation, people (and companies) are more likely to disregard the risk of an activity if the possible harm will happen to someone else. To economists these public harms are called "negative externalities". Air pollution from factories drifting across borders, fish dying downstream from a plant that pollutes the river, and migration routes of animals being altered by transportation corridors are all examples of negative externalities. To economists, negative externalities can be a sign that competitive markets aren't working properly and that regulation might be needed.

For many decisions that have risk, people are free to take chances unless there is a law that says they can't. For example, we are all free to sink our life savings into a legal business venture even if it has a low probability of success. If someone wanted to stop us, they would have to prove that our activity is against a law or at least, harmful to others. We wouldn't have to prove anything.

Because the natural world is complex it can be hard, or even impossible, to prove in advance either the probability or severity of possible harm from taking risks. In many cases we simply don't have the scientific knowledge or the data to accurately predict what could happen if we do something. And for the really big things, the results could be catastrophic and impossible to repair.

To deal with this, the precautionary principle turns the calculation around--someone proposing an activity has to prove that it would not cause an unacceptable level of harm before they do it. Where the precautionary principle applies, governments have a duty to protect the public interest through regulation even when there isn't full scientific...