Two themes have been developed in this work: first, a centralising or uniting theme, in defence of construing and applying all international law, including the WTO treaty, in the context of other norms of international law, be they customary law or other conventions; second, a theme calling for the recognition of the diversity between states and the contractual freedom of states to change their minds and to decide for themselves to which treaty or norm they want to give preference. This second theme is not a centralising or uniting one, but a centrifugal one allowing for regional and state-to-state differences in legal relationships. The tension between these two themes explains why this thesis, though focusing on conflict and conflict resolution, devoted large parts also to the process of accumulation of norms.

The interplay of norms in international law is no longer of academic interest only. In today's interdependent world, where states must co-operate in pursuit of common objectives and do so under the auspices of an ever increasing number of distinct international organisations, the potential for conflict between norms is very real, indeed.