In February 2000, the EuropeanCommission adopted a Communication on theprecautionary principle. This states how theCommission intends to apply the principle andestablishes guidelines for its application. Thedocument is intended to inform discussions oninternational agreements. In particular, itprovides a defense of European Union (EU)precautionary policies in case of tradedisputes, for example, in case the EU isaccused of imposing unfair trade barriers onexports of genetically-modified (GM) productsfrom the United States under the rules of theWorld Trade Organisation. In the communication,the Commission emphasizes the scientificaspects (...) of the precautionary principle, perhapspartly to counter claims from US officials thatthe EU's reluctance to accept GM imports is notbased on science but is politically-motivated.However, a principle is by definition a moralguide to behavior. In other words, it is anethic. The precautionary principle should beviewed as a complement to science, to beinvoked when a lack of scientific evidencemeans that outcomes are uncertain. Anyinterpretation of this principle needs to placeat least as much emphasis on its ethical andvalue-based aspects as on its scientificjustification. The Commission's interpretationrisks undermining the painstaking progress madeamong European Union member states inresponding to public concern about GM crops andfood by adopting increased precaution. Thispaper explores the balance between thescientific and ethical/value-based aspects ofthe precautionary principle as set out in theCommission's communication, to make the casethat it is the ethical and value-based aspectsrather than the scientific aspects of theguidelines that need strengthening. (shrink)