Legal Status of Eastern Greenland(P.C.I.J.)
It is impossible to read the records of the decisions in cases as to territorial sovereignty without observing that in many cases the tribunal has been satisfied with very little in the way of the actual exercise of sovereign rights, provided that the other State could not make out a superior claim. This is particularly true in the case of claims to sovereignty over areas in thinly populated or unsettled countries.
無人島においては他国が優越する主張をしない限り、ほんの僅かな現実の主権の発現が権原となる。

CASE CONCERNING SOVEREIGNTY OVER PULAU LIGITAN AND PULAU SIPADAN(ICJ)
In particular in the case of very small islands which are uninhabited or not permanently inhabited like Ligitan and Sipadan, which have been of little economic importance (at least until recently) effectivites will indeed generally be scarce.
(中略）
The Court finally observes that it can only consider those acts as constituting a relevant display of authority which leave no doubt as to their specific reference to the islands in dispute as such. Regulations or administrative acts of a general nature can therefore be taken as effectivites with regard to Ligitan and Sipadan only if it is clear from their terms or their effects that they pertained to these two islands.
Given the circumstances of the case, and in particular in view of the evidence furnished by the Parties, the Court concludes that Malaysia has title to Ligitan and Sipadan on the basis of the effectivites referred to above.
無人島でも規則や管理活動といった疑義のない具体的な権力の発現が必要。


Maritime Delimitation and Territorial Questions between Qatar and Bahrain(ICJ)
 The Court first notes that Qit'at Jaradah is a very small island situated within the 12-mile limit of both States. According to the report of the expert commissioned by Bahrain, at high tide its length and breadth are about 12 by 4 metres, whereas at low tide they are 600 and 75 metres. At high tide, its altitude is approximately 0.4 metres.
(中略）
 Certain types of activities invoked by Bahrain such as the drilling of artesian wells would, taken by themselves, be considered controversial as acts performed a titre de souverain. The construction of navigational aids, on the other hand, can be legally relevant in the case of very small islands. In the present case, taking into account the size of Qit’at Jaradah, the activi ies carried out by Bahrain on that island must be considered sufficient to support Bahrain’s claim that it has sovereignty over it.
無人島における主権の行使は、権原となる。

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日本の実効支配の疑義のない明確な証拠
望楼建設、島根県による測量、知事の上陸・視察、漁業許可によるアシカ漁　etc.
（これらの日本の主権行使に対する他国からの抗議の表明なし）

1905年以前の韓国の実効支配の疑義のない明確な証拠
無し。

以上より、1905年以前に竹島の権原を韓国が取得したことはなく、1905年の島根編入は有効となる。