The interaction between World Trade Organisation (WTO) law and external international law : the constrained openness of WTO law (a prologue to a theory)

1. Introduction : the fragmented nature of international law -- 2. The inadequacy of the professional tool box of treaty interpretation as an account of fragmentation -- 3. The constrained openness of WTO law -- 4. The debate on the interaction between WTO law and external international law -- 5. The precautionary principle and the WTO agreement on sanitary and phytosanitary measures -- 6. Examples of interaction between WTO law and external international law -- 7. Conclusion.