It requires us to evaluate honestly all the evidence and the uncertainties. The precautionary principle comes into play when decision-makers suspect that a course of action may have harmful effects but are uncertain about their cause and possible extent. It demands more, not less, science in decision-making, relying on multiple lines of evidence from diverse disciplines and constituencies of interest. Holm and Harris contend that the precautionary principle will block innovation. No' does not always mean a prohibition, but can mean any of an array of measures to prevent harm.
Methods exist for regulatory approval of new technologies consistent with the principle.
The gains achieved through 'clean production' methods provide evidence that implementation of the precautionary principle stimulates, not stymies, innovation. Clean production involves the prevention of harm at source through the use of less material-intensive and toxic production systems and products, and was a logical outcome of the principle's demand for preventive action in the face of uncertainty. Holm and Harris suggest that we wait for damage to occur before taking action. Unfortunately we already have a hole in the ozone layer, marine fish stocks are depleted, and climate change threatens future generations. The challenge is to prevent harm before it occurs.