America's tiny but determined band of anti-biotechnology campaigners could have picked no more favourable place than the state of Oregon to ask voters to enact new legislation requiring labelling of any food with even a hint of genetically modified ingredients. The electors' decision in a high-profile mail referendum to culminate 5 November will have far-reaching implications for agricultural biotechnology throughout the US and could influence the global anti-GM movement, argues James C. Webster.