The dilemma between trade liberalisation and environmental protection continues to persist. Sustainable development is a fundamental goal of the World Trade Organisation (WTO). Under WTO rules, states are allowed to implement measures directed to protect the environment, provided that certain conditions are upheld and international trade law is not violated. When a country (the complainant) considers an act of another country (the defendant) a violation of international trade law, they can litigate the defendant in the judicial system of the WTO: the dispute settlement body (DSB). The WTO DSB goal is to settle trade disputes among its members peacefully. The complainants and defendants are seldom the only actors at play in the WTO DSB. Individuals, NGOs, and third parties may join a trade dispute as well. The individual characteristics of each actor can have an influence on the final ruling of the supranational court. This thesis focuses on the role of third parties in particular. Third parties are, similar to the complainant and defendant, countries. Through a social network analysis, the power derived from one’s position in the network is investigated. The scope is limited to trade-environment disputes within the WTO DSB due to the ongoing dilemma between trade liberalisation and environmental protection. The results show that developed economies, and states with high environmental norms are more likely to participate in trade-environment disputes within the WTO DSB. Moreover, the creators of the WTO have the most third party connections. Connections play an important role for creating social power. Lastly, the WTO DSB is more likely to rule in favour of the most powerful states in trade-environment disputes. Future research could take into account the multiplicity of group membership and other types of relations between countries when investigating states’ participation in the WTO DSB.