1. In support of UNESCO's own right to intervene, the preamble (third recital) to the Declaration cites Art I (2)(c) of the Organization's Constitution.
2. See the resolution ‘Acts constituting a crime against the common heritage of humanity’, above at 180. More specifically, UNESCO Doc 31 C/46, para 6 (c) states that the Declaration/would not be intended to create obligations for States, but would restate the fundamental principles of the existing legal instruments…’.
3. Proportionality does not necessarily equate with reciprocity. That is, countermeasures need not involve the breach of an identical obligation. At the same time, reciprocity obviously makes the assessment of proportionality more straightforward.
4. See ARSIWA , Art 51: ‘Countermeasures must be commensurate with the injury suffered, taking into account the gravity of the internationally wrongful act and the rights in question.’
5. Solidarity Measures: State Responsibility as a New International Order;Koskenniemi;BYIL,2001