The ICJ outlined the legal rationale for the supporters of this view in its advisory opinion of 9 July 2004. It noted:
...under customary international law as reflected (...) in Article 42 of the Regulations Respecting the Laws and Customs of War on Land annexed to the Fourth Hague Convention of 18 October 1907 (hereinafter “the Hague Regulations of 1907”), territory is considered occupied when it is actually placed under the authority of the hostile army, and the occupation extends only to the territory where such authority has been established and can be exercised. The territories situated between the Green Line (see paragraph 72 above) and the former eastern boundary of Palestine under the Mandate were occupied by Israel in 1967 during the armed conflict between Israel and Jordan. Under customary international law, these were therefore occupied territories in which Israel had the status of occupying Power. Subsequent events in these territories, as described in paragraphs 75 to 77 above, have done nothing to alter this situation. All these territories (including East Jerusalem) remain occupied territories and Israel has continued to have the status of occupying Power.
On the application of the fourth Geneva Convention, the Court noted:
...for the purpose of determining the scope of application of the Fourth Geneva Convention, it should be recalled that under common Article 2 of the four Conventions of 12 August 1949:
“In addition to the provisions which shall be implemented in peacetime, the present Convention shall apply to all cases of declared war or of any other armed conflict which may arise between two or more of the High Contracting Parties, even if the state of war is not recognized by one of them.
The Convention shall also apply to all cases of partial or total occupation of the territory of a High Contracting Party, even if the said occupation meets with no armed resistance."
(...) the Court notes that, according to the first paragraph of Article 2 of the Fourth Geneva Convention, that Convention is applicable when two conditions are fulfilled: that there exists an armed conflict (whether or not a state of war has been recognized); and that the conflict has arisen between two contracting parties. (...) The object of the second paragraph of Article 2 is not to restrict the scope of application of the Convention, as defined by the first paragraph, by excluding therefrom territories not falling under the sovereignty of one of the contracting parties. It is directed simply to making it clear that, even if occupation effected during the conflict met no armed resistance, the Convention is still applicable.
