This paper examines the ethical andsocial questions that underlie the present UKdiscussion whether GM crops and organicagriculture can co-exist within a given regionor are mutually exclusive. A EuropeanCommission report predicted practicaldifficulties in achieving sufficientseparation distances to guarantee lowerthreshold levels proposed for GM material inorganic produce. Evidence of gene flow betweensome crops and their wild relatives has beena key issue in the recent Government consultation toconsult on whether or not to authorizecommercial planting of GM crops, following theresults of the current UK (...) farm scale trials.The admixture of imported Bt transgenes intolandrace varieties of Mexican maize alsopresents difficulties. An ethical evaluationis made of the claim that organic growersshould expect protection from adventitioustraces of GM constructs in their products. Towhat extent – on either side of the debate –can any particular group in society set upagricultural standards for itself that mayeffectively restrain others from an otherwisejust business? The assumptions behind notionslike ``purity'' and ``contamination'' areexamined, together with their underlying viewsof nature and human intervention. The 2001UK Agriculture and Environmental BiotechnologyCommission report is relevant to theseissues. While the Government wishes to promotethe UK biotechnology industry and is underpressure from US claims of trade restraint, astrong organic lobby demands purity from GMcontamination. Does this adversarial framingof the issues reflect broader public opinionin the UK public consultation? Inarriving at policy decisions, the role of thevirtue of tolerance is considered inpost-modern and Christian ethical contexts. (shrink)