Municipal law is able to recognize abstract rights of property existing apart from any material display of them. IL cannot be presumed to reduce a right such as territorial sovereignty without concrete manifestations [settlement].
A juridical fact must be appreciated in the light of the law contemporary with it, and not of the law in force at the time when a dispute in regard to it arises or falls to be settled. The effect of discovery by Spain is therefore to be determined by the rules of international law in force in the first half of the 16th century … the question arises whether sovereignty yet existed at the critical date, i.e., the moment of the conclusion and coming into force of the Treaty of Paris 
As regards the question which of different legal systems prevailing at successive periods is to be applied in a particular case (the so-called inter-temporal rule) a distinction must be made between the creation of rights and the existence of rights …International law in the 19th century … laid down the principle that occupation to constitute a claim to territorial sovereignty must be effective … discovery alone, without any subsequent act, cannot, at the present time suffice to prove sovereignty over the Island of Palmas
“A juridical fact must be appreciated in the light of the law contemporary with it, and not of the law in force at the time when a dispute in regard to it arises or falls to be settled”
It is evident that Spain could not transfer more rights than she herself possessed.