Ballot Measure 27 of 2002 would have required the mandatory labelling of all genetically modified food sold in the U.S. state of Oregon.
They repeated the belief of some activists that genetic engineering of food poses a potential threat to health and safety.
Proponents also ridiculed the cost estimates of the law brought by the measure's opponents.
Opponents argued that Oregon's agricultural industry would be burdened by excessive costs if the measure were to pass, given the lack of such a requirement throughout the rest of the United States.
In addition, opponents claimed there was little evidence that GMO foods posed a danger to human health.