ABSTRACT
This chapter starts with a brief introduction to customary international law. It then moves on to analyse the two elements of customary law: state practice and opinio juris. With regards to state practice, the chapter argues that the creation of a new customary rule depends on the practice of the "specially affected states". It is essential that the states whose interests are specially affected by the proposed customary rule should be in favour of the creation of this rule. The types of materials and evidence that constitute state behaviour also be analysed. In respect to opinio juris, the chapter argues that it is not necessary to show the existence of opinio juris before a customary rule can be established. The chapter presents that the most crucial factor in creating the proposed customary rule is the concurrence of specially affected states in the field of removal and return of cultural heritage.
