This chapter explores the underlying premises of EU climate law, how they impose themselves upon the relationship between EU climate law and EU trade law, and their bearing upon the relationship between EU climate law and WTO trade rules. The first part of the chapter outlines EU climate law measures and examines their underlying rationale. The second part locates EU climate law within the EU legal order, highlighting its key features and emphasizing the significance of the interrelationship between economic and environmental policy. This focus upon the relationship between environmental and economic policy continues in the third part, which analyses the relationship between EU climate law and other EU law. The interaction of climate law and the trade liberalization rules of the internal market is explored, with a particular analytical focus upon Court of Justice jurisprudence relating to renewable energy. Having identified key features of the EU approach, attention shifts to assessing the impact of the EU’s WTO obligations upon EU climate law. The key WTO provisions and their application are subsequently examined in the light of the above analysis, and some final conclusions and reflections are set out with regard to the relationship between WTO law and climate law.