The dispute between the US and EU over GM foods at the WTO is examined in terms of the issues it raises about protectionism, environmental protection and precaution. The issue of whether GM, GM Derived and Non-GM foods are equivalent to each other is examined using data from a national choice modelling study in the UK. These categories of food are critical since they underpin the EU's new food labelling regime which it hoped would defuse the WTO dispute. The results are analysed using a Bayesian mixed logit model which allows greater flexibility in the modelling of preference distributions than that allowed through classical estimation. The Bayesian approach allows the use of censored normal and Johnson's SB distributions which can accommodate a bounded distribution with a probability mass point at zero (i.e. indifference). This is particularly important where, as in the case of GM food, we may expect some to be indifferent to the food whilst others dislike it, some strongly so. The results indicate bi-modal distributions regarding GM foodtypes, with some indifferent or mildly averse to GM foodtypes and others are strongly averse. A strong finding of the analysis is that most people treat ingredients derived from GM crops (but free from altered DNA) as equivalent to GM ingredients. This supports a labelling regime based on process rather than simply product and suggests considerable consumer benefits from the EU's new GM labelling regime.