University of the Witwatersrand The present working paper is part of a larger project that is underway to characterize the politics of risk based transatlantic trade conflict. In particular, attention is given to the role of science in the process for trade dispute emergence. This working paper suggests that the role of epistemic communities and scientific evidence played an important role in this context of trade conflict and seeks to chart when, where and how science was influential. As such, the contribution lies in systematically in discussing the interplay between political and economic interests and scientific ideas as a means to attempt to understand how all of these variables matter in risk based trade disputes emergence. The formal trade dispute over Hormone-fed beef offers an instance where the US and Canada formally challenged European risk regulations. The succeeding section charts the evolution of this case up to the point of launching a formal WTO dispute, with particular emphasis on the interests present and the role of science used to justify the regulations, the forums used and the influence of epistemic communities to try and bring about a resolution. Whilst, these formal disputes have been the centre of much scholarship, there has been little consideration given to the role of science. Disputing Restrictions on Hormone Fed Beef In 1996 the US and Canada requested separate WTO dispute settlement panels over the EU ban of beef treated with growth hormones. At its root, this dispute was a challenge to the type of science used to justify policy in the EU. European officials consider growth hormones to be carcinogenic and therefore dangerous to human health. Indeed, the scientific evidence suggests that oestrogen, progesterone, testosterone, zeranol, trenbolone and melengestrol acetate (MGA)