This seminar is a foundational seminar on substantive international trade law. It focuses on the core principles of WTO law in the fields of goods and services. In the first part of the seminar, we will study the nondiscrimination principle, as embodied in Article I GATT (Most-Favoured-Nation principle), Article III GATT (National Treatment) and in the corresponding GATT provisions. These are really constitutional-type principles.The second part of the seminar will deal with the Agreements on Technical Barriers to Trade (TBT), and on Sanitary and Phytosanitary Measures (SPS). The TBT and the SPS being largely incomplete contracts, the main focus of the seminar will be on the manner in which they have been completed through case-law so far.