The general principle is that the Convention shall not apply to any
rights or interests pre-existing to the entry into force of the Convention or the
Protocol, respectively.
By declaration a Contracting State may render the new regime applicable to pre-existing rights or interests if a designated period of time has passed.
In absence of such declaration, issues arising in relation to a pre-existing right or interest are governed by the applicable law, and the holder of such right is not affected by the Convention.
However, even if a Contracting State decides to have the Convention applied to pre-existing national rights or interests, it can only do so with respect to the rules of
priority.
The reason for this mechanism is twofold: on one hand, one wants to