A fundamental difference between multilateral trade agreements like the GATT and WTO and preferential trade agreements is the multilateral agreements' inclusion of a most-favoured-nation (MFN) principle. Though this principle requires that members implement policies that provide equal treatment to all GATT/WTO countries, an open question is the extent to which members actually follow the MFN principle when the rules so require. This paper is a first attempt to address this question empirically, and to do so, we use a sample of GATT/WTO trade disputes to investigate the effect of successful dispute settlement negotiations on the trade of third country exporters to the defendant country. We document evidence on the pattern of liberalization resulting from trade disputes that is consistent with defendant countries successfully applying the GATT/WTO's equal treatment rule to the trade of third countries.